functions and functional programming

class: center, middle, inverse, title-slide

# functions and functional programming
### Colin Rundel
### 2019-02-05

---

exclude: true

---
class: middle
count: false

# Functions

---

## When to use functions

The goal of a function is to encapsulate a *small* *reusable* piece of code.

* Name should make it clear what the function does (think in terms of simple verbs).

* Functionality should be simple enough to be quickly understood.

* The smaller and more modular the code the easier it will be to reuse elsewhere.

* **D**ont **R**epeat **Y**ourself - change code in only one location

---

## Function Parts

The two parts of a function are the arguments (`formals`) and the code (`body`).

```r
gcd = function(long1, lat1, long2, lat2) {
  R = 6371 # Earth mean radius in km
  # distance in km
  acos(sin(lat1)*sin(lat2) + cos(lat1)*cos(lat2) * cos(long2-long1)) * R
}
```

.pull-left[

```r
formals(gcd)
```

```
## $long1
## 
## 
## $lat1
## 
## 
## $long2
## 
## 
## $lat2
```
]

.pull-right[

```r
body(gcd)
```

```
## {
##     R = 6371
##     acos(sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(long2 - 
##         long1)) * R
## }
```
]

---

## Argument names

When defining a function we are also implicitly defining names for the arguments, when calling the function we can use these names to pass arguments in a different order.

```r
f = function(x, y, z) {
  paste0("x=",x," y=",y," z=",z)
}
```

.pull-left[

```r
f(1,2,3)
```

```
## [1] "x=1 y=2 z=3"
```

```r
f(z=1,x=2,y=3)
```

```
## [1] "x=2 y=3 z=1"
```
]

.pull-right[

```r
f(y=2,1,3)
```

```
## [1] "x=1 y=2 z=3"
```

```r
f(y=2,1,x=3)
```

```
## [1] "x=3 y=2 z=1"
```
]

```r
f(1,2,3,m=1)
```

```
## Error in f(1, 2, 3, m = 1): unused argument (m = 1)
```

---

## Argument defaults

It is also possible to give function arguments default values so that they don't need to be provided every time the function is called.

```r
f = function(x, y=1, z=1) {
  paste0("x=",x," y=",y," z=",z)
}
```

```r
f()
```

```
## Error in paste0("x=", x, " y=", y, " z=", z): argument "x" is missing, with no default
```

```r
f(x=3)
```

```
## [1] "x=3 y=1 z=1"
```

```r
f(y=2,2)
```

```
## [1] "x=2 y=2 z=1"
```

---

## Scope

R has generous scoping rules, if it can't find a variable in the functions body, it will look for it in the next higher scope, and so on.

```r
y = 1
f = function(x) {
  x+y
}
f(3)
```

```
## [1] 4
```

```r
g = function(x) {
  y=2
  x+y
}
g(3)
```

```
## [1] 5
```

---

Additionally, variables defined within a scope only persist for the duration of that scope, and do not overwrite variables at higher scopes (unless you use the global assignment operator `<<-`, *which you shouldn't*)

```r
x = 1
y = 1
z = 1
f = function() {
    y = 2
    g = function() {
      z = 3
      return(x + y + z)
    }
    return(g())
}
f()
```

```
## [1] 6
```

```r
c(x,y,z)
```

```
## [1] 1 1 1
```

---

## Lazy evaluation

Arguments to R functions are lazily evaluated - meaning they are not evaluated until they are used

```r
f = function(x) {
  cat("Hello world!\n")
  x
}

f(stop())
```

```
## Hello world!
```

```
## Error in f(stop()):
```

---

## Everything is a function

```r
`+`
```

```
## function (e1, e2)  .Primitive("+")
```

```r
typeof(`+`)
```

```
## [1] "builtin"
```

```r
x = 4:1
`+`(x,2)
```

```
## [1] 6 5 4 3
```

---

## Getting details

Prefixing any function name with a `?` will open the related help file for that function.

```r
?`+`
?sum
```

For (most) functions you can see their implementation by entering the function name without parentheses (or using the `body` function).

```r
lm
```

```
## function (formula, data, subset, weights, na.action, method = "qr", 
##     model = TRUE, x = FALSE, y = FALSE, qr = TRUE, singular.ok = TRUE, 
##     contrasts = NULL, offset, ...) 
## {
##     ret.x <- x
##     ret.y <- y
##     cl <- match.call()
##     mf <- match.call(expand.dots = FALSE)
##     m <- match(c("formula", "data", "subset", "weights", "na.action", 
##         "offset"), names(mf), 0L)
##     mf <- mf[c(1L, m)]
##     mf$drop.unused.levels <- TRUE
##     mf[[1L]] <- quote(stats::model.frame)
##     mf <- eval(mf, parent.frame())
##     if (method == "model.frame") 
##         return(mf)
##     else if (method != "qr") 
##         warning(gettextf("method = '%s' is not supported. Using 'qr'", 
##             method), domain = NA)
##     mt <- attr(mf, "terms")
##     y <- model.response(mf, "numeric")
##     w <- as.vector(model.weights(mf))
##     if (!is.null(w) && !is.numeric(w)) 
##         stop("'weights' must be a numeric vector")
##     offset <- as.vector(model.offset(mf))
##     if (!is.null(offset)) {
##         if (length(offset) != NROW(y)) 
##             stop(gettextf("number of offsets is %d, should equal %d (number of observations)", 
##                 length(offset), NROW(y)), domain = NA)
##     }
##     if (is.empty.model(mt)) {
##         x <- NULL
##         z <- list(coefficients = if (is.matrix(y)) matrix(NA_real_, 
##             0, ncol(y)) else numeric(), residuals = y, fitted.values = 0 * 
##             y, weights = w, rank = 0L, df.residual = if (!is.null(w)) sum(w != 
##             0) else if (is.matrix(y)) nrow(y) else length(y))
##         if (!is.null(offset)) {
##             z$fitted.values <- offset
##             z$residuals <- y - offset
##         }
##     }
##     else {
##         x <- model.matrix(mt, mf, contrasts)
##         z <- if (is.null(w)) 
##             lm.fit(x, y, offset = offset, singular.ok = singular.ok, 
##                 ...)
##         else lm.wfit(x, y, w, offset = offset, singular.ok = singular.ok, 
##             ...)
##     }
##     class(z) <- c(if (is.matrix(y)) "mlm", "lm")
##     z$na.action <- attr(mf, "na.action")
##     z$offset <- offset
##     z$contrasts <- attr(x, "contrasts")
##     z$xlevels <- .getXlevels(mt, mf)
##     z$call <- cl
##     z$terms <- mt
##     if (model) 
##         z$model <- mf
##     if (ret.x) 
##         z$x <- x
##     if (ret.y) 
##         z$y <- y
##     if (!qr) 
##         z$qr <- NULL
##     z
## }
## <bytecode: 0x7ffb5def4fa8>
## <environment: namespace:stats>
```

---

## Less Helpful Examples

```r
list
```

```
## function (...)  .Primitive("list")
```

```r
`[`
```

```
## .Primitive("[")
```

```r
sum
```

```
## function (..., na.rm = FALSE)  .Primitive("sum")
```

```r
`+`
```

```
## function (e1, e2)  .Primitive("+")
```

---

## Infix functions (operators)

We can define our own infix functions like `+` or `*`, the only requirement is that they must start and end with a `%`.

```r
`%nand%` = function(x, y) {
  !(x & y)
}
```

.pull-left[

```r
TRUE %nand% TRUE
```

```
## [1] FALSE
```

```r
TRUE %nand% FALSE
```

```
## [1] TRUE
```
]

.pull-right[

```r
FALSE %nand% TRUE
```

```
## [1] TRUE
```

```r
FALSE %nand% FALSE
```

```
## [1] TRUE
```
]

---

## Replacement functions

We can also define functions that allow for 'inplace' modification like `attr` or `names`.

```r
`last<-` = function(x, value) {
  x[length(x)] = value
  x
}
```

```r
x = 1:10
last(x) = 5L
x
```

```
##  [1] 1 2 3 4 5 6 7 8 9 5
```

```r
last(1)
```

```
## Error in last(1): could not find function "last"
```

---

## `...` argument

This is a special argument that captures all arguments that are not matched explicitly. In order to capture the arguments we almost always use `list(...)`.

```r
f = function(x=1, y=2, ...) {
  str(list(...))
}
```

.pull-left[

```r
f(1,2)
```

```
##  list()
```

```r
f(1,2,3)
```

```
## List of 1
##  $ : num 3
```
]

.pull-right[

```r
f(1,2,3,4)
```

```
## List of 2
##  $ : num 3
##  $ : num 4
```

```r
f(z=3)
```

```
## List of 1
##  $ z: num 3
```
]

---
class: middle
count: false

# Functional Programming

---

## Functional Programming

<br/>

.medium[

* First order functions

* Pure functions

* Anonymous functions

* Vectorized functions

* *Closures*

* *Recursion*

]

---
class: middle
count: false

# Apply functions

---

## Apply functions

The apply functions are a collection of tools for functional programming in R, they are variations of the `map` function found in many other languages

```r
??apply
---

## 
## Help files with alias or concept or title matching ‘apply’ using fuzzy
## matching:
## 
## base::apply             Apply Functions Over Array Margins
## base::.subset           Internal Objects in Package 'base'
## base::by                Apply a Function to a Data Frame Split by Factors
## base::eapply            Apply a Function Over Values in an Environment
## base::lapply            Apply a Function over a List or Vector
## base::mapply            Apply a Function to Multiple List or Vector Arguments
## base::rapply            Recursively Apply a Function to a List
## base::tapply            Apply a Function Over a Ragged Array
```

---

## lapply

Usage: `lapply(X, FUN, ...)`

`lapply` returns a list of the same length as `X`, each element of which is the result of applying `FUN` to the corresponding element of `X`.

<br/>

.pull-left[

```r
lapply(1:8, sqrt) %>% str()
```

```
## List of 8
##  $ : num 1
##  $ : num 1.41
##  $ : num 1.73
##  $ : num 2
##  $ : num 2.24
##  $ : num 2.45
##  $ : num 2.65
##  $ : num 2.83
```
]

.pull-right[

```r
lapply(1:8, function(x) (x+1)^2) %>% str()
```

```
## List of 8
##  $ : num 4
##  $ : num 9
##  $ : num 16
##  $ : num 25
##  $ : num 36
##  $ : num 49
##  $ : num 64
##  $ : num 81
```
]

---

```r
lapply(1:8, function(x, pow) x^pow, pow=3) %>% str()
```

```
## List of 8
##  $ : num 1
##  $ : num 8
##  $ : num 27
##  $ : num 64
##  $ : num 125
##  $ : num 216
##  $ : num 343
##  $ : num 512
```

```r
lapply(1:8, function(x, pow) x^pow, x=2) %>% str()
```

```
## List of 8
##  $ : num 2
##  $ : num 4
##  $ : num 8
##  $ : num 16
##  $ : num 32
##  $ : num 64
##  $ : num 128
##  $ : num 256
```

---

## sapply

Usage: `sapply(X, FUN, ..., simplify = TRUE, USE.NAMES = TRUE)`

`sapply` is a *user-friendly* version and wrapper of `lapply`, it is a *simplifying* version of lapply. Whenever possible it will return a vector, matrix, or an array.

<br/>

```r
sapply(1:8, sqrt)
```

```
## [1] 1.000000 1.414214 1.732051 2.000000 2.236068 2.449490 2.645751 2.828427
```

```r
sapply(1:8, function(x) (x+1)^2)
```

```
## [1]  4  9 16 25 36 49 64 81
```

---

```r
sapply(1:8, function(x) c(x, x^2, x^3, x^4))
```

```
##      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
## [1,]    1    2    3    4    5    6    7    8
## [2,]    1    4    9   16   25   36   49   64
## [3,]    1    8   27   64  125  216  343  512
## [4,]    1   16   81  256  625 1296 2401 4096
```

```r
sapply(1:8, function(x) list(x, x^2, x^3, x^4))
```

```
##      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
## [1,] 1    2    3    4    5    6    7    8   
## [2,] 1    4    9    16   25   36   49   64  
## [3,] 1    8    27   64   125  216  343  512 
## [4,] 1    16   81   256  625  1296 2401 4096
```

---

```r
sapply(2:6, seq)
```

```
## [[1]]
## [1] 1 2
## 
## [[2]]
## [1] 1 2 3
## 
## [[3]]
## [1] 1 2 3 4
## 
## [[4]]
## [1] 1 2 3 4 5
## 
## [[5]]
## [1] 1 2 3 4 5 6
```

---

## [ls]apply and data frames

We can use these functions with data frames, the key is to remember that a data frame is just a fancy list.

```r
df = data.frame(a = 1:6, b = letters[1:6], c = c(TRUE,FALSE))
lapply(df, class) %>% str()
```

```
## List of 3
##  $ a: chr "integer"
##  $ b: chr "factor"
##  $ c: chr "logical"
```

```r
sapply(df, class)
```

```
##         a         b         c 
## "integer"  "factor" "logical"
```

---

## other less common applies

* `apply(X, MARGIN, FUN, ...)` - applies a function over the rows or columns of a data frame, matrix or array

* `vapply(X, FUN, FUN.VALUE, ..., USE.NAMES = TRUE)` - is similar to `sapply`, but has a enforced return type and size

* `mapply(FUN, ..., MoreArgs = NULL, SIMPLIFY = TRUE, USE.NAMES = TRUE)` -  like `sapply` but will iterate over multiple vectors at the same time.

* `rapply(object, f, classes = "ANY", deflt = NULL, how = c("unlist", "replace", "list"), ...)` - a recursive version of `lapply`, behavior depends largely on the `how` argument

* `eapply(env, FUN, ..., all.names = FALSE, USE.NAMES = TRUE)` -  apply a function over an environment.

---

## Example 1

Using the `sw_people` data set in the `repurrrsive` package, extract the names of all of the characters using:

* a for loop

* one of the apply functions

---
class: middle
count: false

# purrr

---

## purrr

.center[
<img src="imgs/purrr.png" width="231" />
]

A tidyverse package which improves the functional programming tools in R, it focuses on *pure* and *type stable* functions.

---

## Map functions

Basic functions for looping over an object and returning a value (of a specific type) - replacement for `lapply`/`sapply`/`vapply`.

* `map()` - returns a list.

* `map_lgl()` - returns a logical vector.

* `map_int()` - returns a integer vector.

* `map_dbl()` - returns a double vector.

* `map_chr()` - returns a character vector.

* `map_df()` / `map_dfr()` - returns a data frame by row binding.

* `map_dfc()` - returns a data frame by column binding.

* `walk()` - returns nothing, call function exclusively for its side effects

---

## Type Consistency

R is a weakly / dynamically typed language which means there is no simple way to define a function which enforces the argument or return types. This flexibility can be useful at times, but often it makes it hard to reason about your code and requires more verbose code to handle edge cases.

```r
x = list(rnorm(1e3),rnorm(1e3),rnorm(1e3))
```

```r
map_dbl(x, mean)
```

```
## [1]  0.004410831 -0.053991815 -0.009216712
```

```r
map_chr(x, mean)
```

```
## [1] "0.004411"  "-0.053992" "-0.009217"
```

```r
map_int(x, mean)
```

```
## Error: Can't coerce element 1 from a double to a integer
```

---

## Shortcut - Anonymous Functions

An anonymous function is one that is never given a name (assigned to a variable)

```r
sapply(1:5, function(x) x^(x+1))
```

```
## [1]     1     8    81  1024 15625
```

purrr lets us write anonymous functions using one sided formulas where the argument is given by `.` or `.x` for `map` and related functions.

```r
map_dbl(1:5, ~ .^(.+1))
```

```
## [1]     1     8    81  1024 15625
```

```r
map_dbl(1:5, ~ .x^(.x+1))
```

```
## [1]     1     8    81  1024 15625
```

---

## Shortcut - Anonymous Functions - `map2`

Functions with the `map2` prefix work the same as the `map` functions but they iterate over two vectors instead of one. Arguments are instead given by `.x` and `.y` (or `..1` and `..2`) respectively.

```r
map2_dbl(1:5, 1:5, ~ .x^(.y+1))
```

```
## [1]     1     8    81  1024 15625
```

```r
map2_dbl(1:5, 1:5, ~ ..1^(..2+1))
```

```
## [1]     1     8    81  1024 15625
```

```r
map2_chr(letters[1:5], LETTERS[1:5], paste0)
```

```
## [1] "aA" "bB" "cC" "dD" "eE"
```

---

## Purrr shortcut - Lookups

Very often we want to extract only certain (named) values from a list, `purrr` provides a shortcut for this operation when you provide either a character or numeric value instead of a function to apply.

```r
x = list(list(a=1L,b=2L,c=list(d=3L,e=4L)),
         list(a=5L,b=6L,c=list(d=7L,e=8L,f=9L)))
```

.pull-left[

```r
map_int(x, "a")
```

```
## [1] 1 5
```

```r
map_dbl(x, c("c","e"))
```

```
## [1] 4 8
```

```r
map_chr(x, list(3,"d"))
```

```
## [1] "3" "7"
```
]

.pull-right[

```r
map_df(x, 3)
```

```
## # A tibble: 2 x 3
##       d     e     f
##   <int> <int> <int>
## 1     3     4    NA
## 2     7     8     9
```

```r
map_dfc(x, 3)
```

```
## # A tibble: 1 x 5
##       d     e    d1    e1     f
##   <int> <int> <int> <int> <int>
## 1     3     4     7     8     9
```
]

---

```r
x = list(list(a=1L,b=2L,c=list(d=3L,e=4L)),
         list(a=5L,b=6L,c=list(d=7L,e=8L,f=9L)))
```

```r
map(x, list(3,"f"))
```

```
## [[1]]
## NULL
## 
## [[2]]
## [1] 9
```

```r
map_int(x, list(3,"f"))
```

```
## Error: Result 1 is not a length 1 atomic vector
```

```r
map_int(x, list(3,"f"), .default=NA)
```

```
## [1] NA  9
```

---

## Example 2

Using the `sw_people` data set again, generate a tidy data frame (tibble) containing as many details as possible.

```r
library(repurrrsive)
```

.pull-left[

```r
str(sw_people,max.level = 1)
```

```
## List of 87
##  $ :List of 16
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 16
##  $ :List of 16
##  $ :List of 14
##  $ :List of 16
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 16
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 15
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 13
##  $ :List of 14
##  $ :List of 16
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 13
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 16
##  $ :List of 14
##  $ :List of 14
##  $ :List of 13
##  $ :List of 14
##  $ :List of 14
##  $ :List of 14
##  $ :List of 15
##  $ :List of 14
##  $ :List of 13
##  $ :List of 15
```
]

.pull-right[

```r
str(sw_people,max.level = 2)
```

```
## List of 87
##  $ :List of 16
##   ..$ name      : chr "Luke Skywalker"
##   ..$ height    : chr "172"
##   ..$ mass      : chr "77"
##   ..$ hair_color: chr "blond"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "19BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:5] "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/" "http://swapi.co/api/films/1/" ...
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr [1:2] "http://swapi.co/api/vehicles/14/" "http://swapi.co/api/vehicles/30/"
##   ..$ starships : chr [1:2] "http://swapi.co/api/starships/12/" "http://swapi.co/api/starships/22/"
##   ..$ created   : chr "2014-12-09T13:50:51.644000Z"
##   ..$ edited    : chr "2014-12-20T21:17:56.891000Z"
##   ..$ url       : chr "http://swapi.co/api/people/1/"
##  $ :List of 14
##   ..$ name      : chr "C-3PO"
##   ..$ height    : chr "167"
##   ..$ mass      : chr "75"
##   ..$ hair_color: chr "n/a"
##   ..$ skin_color: chr "gold"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "112BBY"
##   ..$ gender    : chr "n/a"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:6] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" ...
##   ..$ species   : chr "http://swapi.co/api/species/2/"
##   ..$ created   : chr "2014-12-10T15:10:51.357000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.309000Z"
##   ..$ url       : chr "http://swapi.co/api/people/2/"
##  $ :List of 14
##   ..$ name      : chr "R2-D2"
##   ..$ height    : chr "96"
##   ..$ mass      : chr "32"
##   ..$ hair_color: chr "n/a"
##   ..$ skin_color: chr "white, blue"
##   ..$ eye_color : chr "red"
##   ..$ birth_year: chr "33BBY"
##   ..$ gender    : chr "n/a"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr [1:7] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" ...
##   ..$ species   : chr "http://swapi.co/api/species/2/"
##   ..$ created   : chr "2014-12-10T15:11:50.376000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.311000Z"
##   ..$ url       : chr "http://swapi.co/api/people/3/"
##  $ :List of 15
##   ..$ name      : chr "Darth Vader"
##   ..$ height    : chr "202"
##   ..$ mass      : chr "136"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "white"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "41.9BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:4] "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/13/"
##   ..$ created   : chr "2014-12-10T15:18:20.704000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.313000Z"
##   ..$ url       : chr "http://swapi.co/api/people/4/"
##  $ :List of 15
##   ..$ name      : chr "Leia Organa"
##   ..$ height    : chr "150"
##   ..$ mass      : chr "49"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "19BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/2/"
##   ..$ films     : chr [1:5] "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/" "http://swapi.co/api/films/1/" ...
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/30/"
##   ..$ created   : chr "2014-12-10T15:20:09.791000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.315000Z"
##   ..$ url       : chr "http://swapi.co/api/people/5/"
##  $ :List of 14
##   ..$ name      : chr "Owen Lars"
##   ..$ height    : chr "178"
##   ..$ mass      : chr "120"
##   ..$ hair_color: chr "brown, grey"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "52BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-10T15:52:14.024000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.317000Z"
##   ..$ url       : chr "http://swapi.co/api/people/6/"
##  $ :List of 14
##   ..$ name      : chr "Beru Whitesun lars"
##   ..$ height    : chr "165"
##   ..$ mass      : chr "75"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "47BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-10T15:53:41.121000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.319000Z"
##   ..$ url       : chr "http://swapi.co/api/people/7/"
##  $ :List of 14
##   ..$ name      : chr "R5-D4"
##   ..$ height    : chr "97"
##   ..$ mass      : chr "32"
##   ..$ hair_color: chr "n/a"
##   ..$ skin_color: chr "white, red"
##   ..$ eye_color : chr "red"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "n/a"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/2/"
##   ..$ created   : chr "2014-12-10T15:57:50.959000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.321000Z"
##   ..$ url       : chr "http://swapi.co/api/people/8/"
##  $ :List of 15
##   ..$ name      : chr "Biggs Darklighter"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "84"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "24BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/12/"
##   ..$ created   : chr "2014-12-10T15:59:50.509000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.323000Z"
##   ..$ url       : chr "http://swapi.co/api/people/9/"
##  $ :List of 16
##   ..$ name      : chr "Obi-Wan Kenobi"
##   ..$ height    : chr "182"
##   ..$ mass      : chr "77"
##   ..$ hair_color: chr "auburn, white"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue-gray"
##   ..$ birth_year: chr "57BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/20/"
##   ..$ films     : chr [1:6] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" ...
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/38/"
##   ..$ starships : chr [1:5] "http://swapi.co/api/starships/48/" "http://swapi.co/api/starships/59/" "http://swapi.co/api/starships/64/" "http://swapi.co/api/starships/65/" ...
##   ..$ created   : chr "2014-12-10T16:16:29.192000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.325000Z"
##   ..$ url       : chr "http://swapi.co/api/people/10/"
##  $ :List of 16
##   ..$ name      : chr "Anakin Skywalker"
##   ..$ height    : chr "188"
##   ..$ mass      : chr "84"
##   ..$ hair_color: chr "blond"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "41.9BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr [1:2] "http://swapi.co/api/vehicles/44/" "http://swapi.co/api/vehicles/46/"
##   ..$ starships : chr [1:3] "http://swapi.co/api/starships/59/" "http://swapi.co/api/starships/65/" "http://swapi.co/api/starships/39/"
##   ..$ created   : chr "2014-12-10T16:20:44.310000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.327000Z"
##   ..$ url       : chr "http://swapi.co/api/people/11/"
##  $ :List of 14
##   ..$ name      : chr "Wilhuff Tarkin"
##   ..$ height    : chr "180"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "auburn, grey"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "64BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/21/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/6/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-10T16:26:56.138000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.330000Z"
##   ..$ url       : chr "http://swapi.co/api/people/12/"
##  $ :List of 16
##   ..$ name      : chr "Chewbacca"
##   ..$ height    : chr "228"
##   ..$ mass      : chr "112"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "unknown"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "200BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/14/"
##   ..$ films     : chr [1:5] "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/" "http://swapi.co/api/films/1/" ...
##   ..$ species   : chr "http://swapi.co/api/species/3/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/19/"
##   ..$ starships : chr [1:2] "http://swapi.co/api/starships/10/" "http://swapi.co/api/starships/22/"
##   ..$ created   : chr "2014-12-10T16:42:45.066000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.332000Z"
##   ..$ url       : chr "http://swapi.co/api/people/13/"
##  $ :List of 15
##   ..$ name      : chr "Han Solo"
##   ..$ height    : chr "180"
##   ..$ mass      : chr "80"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "29BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/22/"
##   ..$ films     : chr [1:4] "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/" "http://swapi.co/api/films/1/" "http://swapi.co/api/films/7/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr [1:2] "http://swapi.co/api/starships/10/" "http://swapi.co/api/starships/22/"
##   ..$ created   : chr "2014-12-10T16:49:14.582000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.334000Z"
##   ..$ url       : chr "http://swapi.co/api/people/14/"
##  $ :List of 14
##   ..$ name      : chr "Greedo"
##   ..$ height    : chr "173"
##   ..$ mass      : chr "74"
##   ..$ hair_color: chr "n/a"
##   ..$ skin_color: chr "green"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "44BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/23/"
##   ..$ films     : chr "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/4/"
##   ..$ created   : chr "2014-12-10T17:03:30.334000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.336000Z"
##   ..$ url       : chr "http://swapi.co/api/people/15/"
##  $ :List of 14
##   ..$ name      : chr "Jabba Desilijic Tiure"
##   ..$ height    : chr "175"
##   ..$ mass      : chr "1,358"
##   ..$ hair_color: chr "n/a"
##   ..$ skin_color: chr "green-tan, brown"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "600BBY"
##   ..$ gender    : chr "hermaphrodite"
##   ..$ homeworld : chr "http://swapi.co/api/planets/24/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/4/" "http://swapi.co/api/films/3/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/5/"
##   ..$ created   : chr "2014-12-10T17:11:31.638000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.338000Z"
##   ..$ url       : chr "http://swapi.co/api/people/16/"
##  $ :List of 16
##   ..$ name      : chr "Wedge Antilles"
##   ..$ height    : chr "170"
##   ..$ mass      : chr "77"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "hazel"
##   ..$ birth_year: chr "21BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/22/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/14/"
##   ..$ starships : chr "http://swapi.co/api/starships/12/"
##   ..$ created   : chr "2014-12-12T11:08:06.469000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.341000Z"
##   ..$ url       : chr "http://swapi.co/api/people/18/"
##  $ :List of 15
##   ..$ name      : chr "Jek Tono Porkins"
##   ..$ height    : chr "180"
##   ..$ mass      : chr "110"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/26/"
##   ..$ films     : chr "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/12/"
##   ..$ created   : chr "2014-12-12T11:16:56.569000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.343000Z"
##   ..$ url       : chr "http://swapi.co/api/people/19/"
##  $ :List of 14
##   ..$ name      : chr "Yoda"
##   ..$ height    : chr "66"
##   ..$ mass      : chr "17"
##   ..$ hair_color: chr "white"
##   ..$ skin_color: chr "green"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "896BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr [1:5] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" ...
##   ..$ species   : chr "http://swapi.co/api/species/6/"
##   ..$ created   : chr "2014-12-15T12:26:01.042000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.345000Z"
##   ..$ url       : chr "http://swapi.co/api/people/20/"
##  $ :List of 14
##   ..$ name      : chr "Palpatine"
##   ..$ height    : chr "170"
##   ..$ mass      : chr "75"
##   ..$ hair_color: chr "grey"
##   ..$ skin_color: chr "pale"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "82BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr [1:5] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/" "http://swapi.co/api/films/3/" ...
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-15T12:48:05.971000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.347000Z"
##   ..$ url       : chr "http://swapi.co/api/people/21/"
##  $ :List of 15
##   ..$ name      : chr "Boba Fett"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "78.2"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "31.5BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/10/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/21/"
##   ..$ created   : chr "2014-12-15T12:49:32.457000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.349000Z"
##   ..$ url       : chr "http://swapi.co/api/people/22/"
##  $ :List of 14
##   ..$ name      : chr "IG-88"
##   ..$ height    : chr "200"
##   ..$ mass      : chr "140"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "metal"
##   ..$ eye_color : chr "red"
##   ..$ birth_year: chr "15BBY"
##   ..$ gender    : chr "none"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/2/"
##   ..$ species   : chr "http://swapi.co/api/species/2/"
##   ..$ created   : chr "2014-12-15T12:51:10.076000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.351000Z"
##   ..$ url       : chr "http://swapi.co/api/people/23/"
##  $ :List of 14
##   ..$ name      : chr "Bossk"
##   ..$ height    : chr "190"
##   ..$ mass      : chr "113"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "green"
##   ..$ eye_color : chr "red"
##   ..$ birth_year: chr "53BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/29/"
##   ..$ films     : chr "http://swapi.co/api/films/2/"
##   ..$ species   : chr "http://swapi.co/api/species/7/"
##   ..$ created   : chr "2014-12-15T12:53:49.297000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.355000Z"
##   ..$ url       : chr "http://swapi.co/api/people/24/"
##  $ :List of 15
##   ..$ name      : chr "Lando Calrissian"
##   ..$ height    : chr "177"
##   ..$ mass      : chr "79"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "dark"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "31BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/30/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/3/" "http://swapi.co/api/films/2/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/10/"
##   ..$ created   : chr "2014-12-15T12:56:32.683000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.357000Z"
##   ..$ url       : chr "http://swapi.co/api/people/25/"
##  $ :List of 14
##   ..$ name      : chr "Lobot"
##   ..$ height    : chr "175"
##   ..$ mass      : chr "79"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "37BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/6/"
##   ..$ films     : chr "http://swapi.co/api/films/2/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-15T13:01:57.178000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.359000Z"
##   ..$ url       : chr "http://swapi.co/api/people/26/"
##  $ :List of 14
##   ..$ name      : chr "Ackbar"
##   ..$ height    : chr "180"
##   ..$ mass      : chr "83"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "brown mottle"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "41BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/31/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/3/" "http://swapi.co/api/films/7/"
##   ..$ species   : chr "http://swapi.co/api/species/8/"
##   ..$ created   : chr "2014-12-18T11:07:50.584000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.362000Z"
##   ..$ url       : chr "http://swapi.co/api/people/27/"
##  $ :List of 14
##   ..$ name      : chr "Mon Mothma"
##   ..$ height    : chr "150"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "auburn"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "48BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/32/"
##   ..$ films     : chr "http://swapi.co/api/films/3/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-18T11:12:38.895000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.364000Z"
##   ..$ url       : chr "http://swapi.co/api/people/28/"
##  $ :List of 15
##   ..$ name      : chr "Arvel Crynyd"
##   ..$ height    : chr "unknown"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/3/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/28/"
##   ..$ created   : chr "2014-12-18T11:16:33.020000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.367000Z"
##   ..$ url       : chr "http://swapi.co/api/people/29/"
##  $ :List of 14
##   ..$ name      : chr "Wicket Systri Warrick"
##   ..$ height    : chr "88"
##   ..$ mass      : chr "20"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "brown"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "8BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/7/"
##   ..$ films     : chr "http://swapi.co/api/films/3/"
##   ..$ species   : chr "http://swapi.co/api/species/9/"
##   ..$ created   : chr "2014-12-18T11:21:58.954000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.369000Z"
##   ..$ url       : chr "http://swapi.co/api/people/30/"
##  $ :List of 15
##   ..$ name      : chr "Nien Nunb"
##   ..$ height    : chr "160"
##   ..$ mass      : chr "68"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/33/"
##   ..$ films     : chr "http://swapi.co/api/films/3/"
##   ..$ species   : chr "http://swapi.co/api/species/10/"
##   ..$ starships : chr "http://swapi.co/api/starships/10/"
##   ..$ created   : chr "2014-12-18T11:26:18.541000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.371000Z"
##   ..$ url       : chr "http://swapi.co/api/people/31/"
##  $ :List of 15
##   ..$ name      : chr "Qui-Gon Jinn"
##   ..$ height    : chr "193"
##   ..$ mass      : chr "89"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "92BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/38/"
##   ..$ created   : chr "2014-12-19T16:54:53.618000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.375000Z"
##   ..$ url       : chr "http://swapi.co/api/people/32/"
##  $ :List of 14
##   ..$ name      : chr "Nute Gunray"
##   ..$ height    : chr "191"
##   ..$ mass      : chr "90"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "mottled green"
##   ..$ eye_color : chr "red"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/18/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/11/"
##   ..$ created   : chr "2014-12-19T17:05:57.357000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.377000Z"
##   ..$ url       : chr "http://swapi.co/api/people/33/"
##  $ :List of 14
##   ..$ name      : chr "Finis Valorum"
##   ..$ height    : chr "170"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "blond"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "91BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/9/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-19T17:21:45.915000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.379000Z"
##   ..$ url       : chr "http://swapi.co/api/people/34/"
##  $ :List of 14
##   ..$ name      : chr "Jar Jar Binks"
##   ..$ height    : chr "196"
##   ..$ mass      : chr "66"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "orange"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "52BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/12/"
##   ..$ created   : chr "2014-12-19T17:29:32.489000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.383000Z"
##   ..$ url       : chr "http://swapi.co/api/people/36/"
##  $ :List of 14
##   ..$ name      : chr "Roos Tarpals"
##   ..$ height    : chr "224"
##   ..$ mass      : chr "82"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/12/"
##   ..$ created   : chr "2014-12-19T17:32:56.741000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.385000Z"
##   ..$ url       : chr "http://swapi.co/api/people/37/"
##  $ :List of 14
##   ..$ name      : chr "Rugor Nass"
##   ..$ height    : chr "206"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "green"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/12/"
##   ..$ created   : chr "2014-12-19T17:33:38.909000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.388000Z"
##   ..$ url       : chr "http://swapi.co/api/people/38/"
##  $ :List of 14
##   ..$ name      : chr "Ric Olié"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ starships : chr "http://swapi.co/api/starships/40/"
##   ..$ created   : chr "2014-12-19T17:45:01.522000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.392000Z"
##   ..$ url       : chr "http://swapi.co/api/people/39/"
##  $ :List of 14
##   ..$ name      : chr "Watto"
##   ..$ height    : chr "137"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "blue, grey"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/34/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/13/"
##   ..$ created   : chr "2014-12-19T17:48:54.647000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.395000Z"
##   ..$ url       : chr "http://swapi.co/api/people/40/"
##  $ :List of 14
##   ..$ name      : chr "Sebulba"
##   ..$ height    : chr "112"
##   ..$ mass      : chr "40"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey, red"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/35/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/14/"
##   ..$ created   : chr "2014-12-19T17:53:02.586000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.397000Z"
##   ..$ url       : chr "http://swapi.co/api/people/41/"
##  $ :List of 13
##   ..$ name      : chr "Quarsh Panaka"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "dark"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "62BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ created   : chr "2014-12-19T17:55:43.348000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.399000Z"
##   ..$ url       : chr "http://swapi.co/api/people/42/"
##  $ :List of 14
##   ..$ name      : chr "Shmi Skywalker"
##   ..$ height    : chr "163"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "72BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-19T17:57:41.191000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.401000Z"
##   ..$ url       : chr "http://swapi.co/api/people/43/"
##  $ :List of 16
##   ..$ name      : chr "Darth Maul"
##   ..$ height    : chr "175"
##   ..$ mass      : chr "80"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "red"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "54BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/36/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/22/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/42/"
##   ..$ starships : chr "http://swapi.co/api/starships/41/"
##   ..$ created   : chr "2014-12-19T18:00:41.929000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.403000Z"
##   ..$ url       : chr "http://swapi.co/api/people/44/"
##  $ :List of 14
##   ..$ name      : chr "Bib Fortuna"
##   ..$ height    : chr "180"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "pale"
##   ..$ eye_color : chr "pink"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/37/"
##   ..$ films     : chr "http://swapi.co/api/films/3/"
##   ..$ species   : chr "http://swapi.co/api/species/15/"
##   ..$ created   : chr "2014-12-20T09:47:02.512000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.407000Z"
##   ..$ url       : chr "http://swapi.co/api/people/45/"
##  $ :List of 14
##   ..$ name      : chr "Ayla Secura"
##   ..$ height    : chr "178"
##   ..$ mass      : chr "55"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "blue"
##   ..$ eye_color : chr "hazel"
##   ..$ birth_year: chr "48BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/37/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/15/"
##   ..$ created   : chr "2014-12-20T09:48:01.172000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.409000Z"
##   ..$ url       : chr "http://swapi.co/api/people/46/"
##  $ :List of 14
##   ..$ name      : chr "Dud Bolt"
##   ..$ height    : chr "94"
##   ..$ mass      : chr "45"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "blue, grey"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/39/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/17/"
##   ..$ created   : chr "2014-12-20T09:57:31.858000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.414000Z"
##   ..$ url       : chr "http://swapi.co/api/people/48/"
##  $ :List of 14
##   ..$ name      : chr "Gasgano"
##   ..$ height    : chr "122"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "white, blue"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/40/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/18/"
##   ..$ created   : chr "2014-12-20T10:02:12.223000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.416000Z"
##   ..$ url       : chr "http://swapi.co/api/people/49/"
##  $ :List of 14
##   ..$ name      : chr "Ben Quadinaros"
##   ..$ height    : chr "163"
##   ..$ mass      : chr "65"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey, green, yellow"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/41/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/19/"
##   ..$ created   : chr "2014-12-20T10:08:33.777000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.417000Z"
##   ..$ url       : chr "http://swapi.co/api/people/50/"
##  $ :List of 14
##   ..$ name      : chr "Mace Windu"
##   ..$ height    : chr "188"
##   ..$ mass      : chr "84"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "dark"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "72BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/42/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T10:12:30.846000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.420000Z"
##   ..$ url       : chr "http://swapi.co/api/people/51/"
##  $ :List of 14
##   ..$ name      : chr "Ki-Adi-Mundi"
##   ..$ height    : chr "198"
##   ..$ mass      : chr "82"
##   ..$ hair_color: chr "white"
##   ..$ skin_color: chr "pale"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "92BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/43/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/20/"
##   ..$ created   : chr "2014-12-20T10:15:32.293000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.422000Z"
##   ..$ url       : chr "http://swapi.co/api/people/52/"
##  $ :List of 14
##   ..$ name      : chr "Kit Fisto"
##   ..$ height    : chr "196"
##   ..$ mass      : chr "87"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "green"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/44/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/21/"
##   ..$ created   : chr "2014-12-20T10:18:57.202000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.424000Z"
##   ..$ url       : chr "http://swapi.co/api/people/53/"
##  $ :List of 14
##   ..$ name      : chr "Eeth Koth"
##   ..$ height    : chr "171"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "brown"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/45/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/22/"
##   ..$ created   : chr "2014-12-20T10:26:47.902000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.427000Z"
##   ..$ url       : chr "http://swapi.co/api/people/54/"
##  $ :List of 14
##   ..$ name      : chr "Adi Gallia"
##   ..$ height    : chr "184"
##   ..$ mass      : chr "50"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "dark"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/9/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/23/"
##   ..$ created   : chr "2014-12-20T10:29:11.661000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.432000Z"
##   ..$ url       : chr "http://swapi.co/api/people/55/"
##  $ :List of 14
##   ..$ name      : chr "Saesee Tiin"
##   ..$ height    : chr "188"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "pale"
##   ..$ eye_color : chr "orange"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/47/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/24/"
##   ..$ created   : chr "2014-12-20T10:32:11.669000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.434000Z"
##   ..$ url       : chr "http://swapi.co/api/people/56/"
##  $ :List of 14
##   ..$ name      : chr "Yarael Poof"
##   ..$ height    : chr "264"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "white"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/48/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/25/"
##   ..$ created   : chr "2014-12-20T10:34:48.725000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.437000Z"
##   ..$ url       : chr "http://swapi.co/api/people/57/"
##  $ :List of 15
##   ..$ name      : chr "Plo Koon"
##   ..$ height    : chr "188"
##   ..$ mass      : chr "80"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "orange"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "22BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/49/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/26/"
##   ..$ starships : chr "http://swapi.co/api/starships/48/"
##   ..$ created   : chr "2014-12-20T10:49:19.859000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.439000Z"
##   ..$ url       : chr "http://swapi.co/api/people/58/"
##  $ :List of 14
##   ..$ name      : chr "Mas Amedda"
##   ..$ height    : chr "196"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "blue"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/50/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/27/"
##   ..$ created   : chr "2014-12-20T10:53:26.457000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.442000Z"
##   ..$ url       : chr "http://swapi.co/api/people/59/"
##  $ :List of 15
##   ..$ name      : chr "Gregar Typho"
##   ..$ height    : chr "185"
##   ..$ mass      : chr "85"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "dark"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/39/"
##   ..$ created   : chr "2014-12-20T11:10:10.381000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.445000Z"
##   ..$ url       : chr "http://swapi.co/api/people/60/"
##  $ :List of 14
##   ..$ name      : chr "Cordé"
##   ..$ height    : chr "157"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T11:11:39.630000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.449000Z"
##   ..$ url       : chr "http://swapi.co/api/people/61/"
##  $ :List of 14
##   ..$ name      : chr "Cliegg Lars"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "82BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/1/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T15:59:03.958000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.451000Z"
##   ..$ url       : chr "http://swapi.co/api/people/62/"
##  $ :List of 14
##   ..$ name      : chr "Poggle the Lesser"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "80"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "green"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/11/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/28/"
##   ..$ created   : chr "2014-12-20T16:40:43.977000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.453000Z"
##   ..$ url       : chr "http://swapi.co/api/people/63/"
##  $ :List of 14
##   ..$ name      : chr "Luminara Unduli"
##   ..$ height    : chr "170"
##   ..$ mass      : chr "56.2"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "yellow"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "58BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/51/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/29/"
##   ..$ created   : chr "2014-12-20T16:45:53.668000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.455000Z"
##   ..$ url       : chr "http://swapi.co/api/people/64/"
##  $ :List of 14
##   ..$ name      : chr "Barriss Offee"
##   ..$ height    : chr "166"
##   ..$ mass      : chr "50"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "yellow"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "40BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/51/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/29/"
##   ..$ created   : chr "2014-12-20T16:46:40.440000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.457000Z"
##   ..$ url       : chr "http://swapi.co/api/people/65/"
##  $ :List of 14
##   ..$ name      : chr "Dormé"
##   ..$ height    : chr "165"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T16:49:14.640000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.460000Z"
##   ..$ url       : chr "http://swapi.co/api/people/66/"
##  $ :List of 15
##   ..$ name      : chr "Dooku"
##   ..$ height    : chr "193"
##   ..$ mass      : chr "80"
##   ..$ hair_color: chr "white"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "102BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/52/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/55/"
##   ..$ created   : chr "2014-12-20T16:52:14.726000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.462000Z"
##   ..$ url       : chr "http://swapi.co/api/people/67/"
##  $ :List of 14
##   ..$ name      : chr "Bail Prestor Organa"
##   ..$ height    : chr "191"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "tan"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "67BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/2/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T16:53:08.575000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.463000Z"
##   ..$ url       : chr "http://swapi.co/api/people/68/"
##  $ :List of 14
##   ..$ name      : chr "Jango Fett"
##   ..$ height    : chr "183"
##   ..$ mass      : chr "79"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "tan"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "66BBY"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/53/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T16:54:41.620000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.465000Z"
##   ..$ url       : chr "http://swapi.co/api/people/69/"
##  $ :List of 15
##   ..$ name      : chr "Zam Wesell"
##   ..$ height    : chr "168"
##   ..$ mass      : chr "55"
##   ..$ hair_color: chr "blonde"
##   ..$ skin_color: chr "fair, green, yellow"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/54/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/30/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/45/"
##   ..$ created   : chr "2014-12-20T16:57:44.471000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.468000Z"
##   ..$ url       : chr "http://swapi.co/api/people/70/"
##  $ :List of 14
##   ..$ name      : chr "Dexter Jettster"
##   ..$ height    : chr "198"
##   ..$ mass      : chr "102"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "brown"
##   ..$ eye_color : chr "yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/55/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/31/"
##   ..$ created   : chr "2014-12-20T17:28:27.248000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.470000Z"
##   ..$ url       : chr "http://swapi.co/api/people/71/"
##  $ :List of 14
##   ..$ name      : chr "Lama Su"
##   ..$ height    : chr "229"
##   ..$ mass      : chr "88"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/10/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/32/"
##   ..$ created   : chr "2014-12-20T17:30:50.416000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.473000Z"
##   ..$ url       : chr "http://swapi.co/api/people/72/"
##  $ :List of 14
##   ..$ name      : chr "Taun We"
##   ..$ height    : chr "213"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/10/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/32/"
##   ..$ created   : chr "2014-12-20T17:31:21.195000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.474000Z"
##   ..$ url       : chr "http://swapi.co/api/people/73/"
##  $ :List of 14
##   ..$ name      : chr "Jocasta Nu"
##   ..$ height    : chr "167"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "white"
##   ..$ skin_color: chr "fair"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/9/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T17:32:51.996000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.476000Z"
##   ..$ url       : chr "http://swapi.co/api/people/74/"
##  $ :List of 14
##   ..$ name      : chr "Ratts Tyerell"
##   ..$ height    : chr "79"
##   ..$ mass      : chr "15"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey, blue"
##   ..$ eye_color : chr "unknown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/38/"
##   ..$ films     : chr "http://swapi.co/api/films/4/"
##   ..$ species   : chr "http://swapi.co/api/species/16/"
##   ..$ created   : chr "2014-12-20T09:53:15.086000Z"
##   ..$ edited    : chr "2016-06-30T12:52:19.604868Z"
##   ..$ url       : chr "http://swapi.co/api/people/47/"
##  $ :List of 13
##   ..$ name      : chr "R4-P17"
##   ..$ height    : chr "96"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "silver, red"
##   ..$ eye_color : chr "red, blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ created   : chr "2014-12-20T17:43:36.409000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.478000Z"
##   ..$ url       : chr "http://swapi.co/api/people/75/"
##  $ :List of 14
##   ..$ name      : chr "Wat Tambor"
##   ..$ height    : chr "193"
##   ..$ mass      : chr "48"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "green, grey"
##   ..$ eye_color : chr "unknown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/56/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/33/"
##   ..$ created   : chr "2014-12-20T17:53:52.607000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.481000Z"
##   ..$ url       : chr "http://swapi.co/api/people/76/"
##  $ :List of 14
##   ..$ name      : chr "San Hill"
##   ..$ height    : chr "191"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey"
##   ..$ eye_color : chr "gold"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/57/"
##   ..$ films     : chr "http://swapi.co/api/films/5/"
##   ..$ species   : chr "http://swapi.co/api/species/34/"
##   ..$ created   : chr "2014-12-20T17:58:17.049000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.484000Z"
##   ..$ url       : chr "http://swapi.co/api/people/77/"
##  $ :List of 14
##   ..$ name      : chr "Shaak Ti"
##   ..$ height    : chr "178"
##   ..$ mass      : chr "57"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "red, blue, white"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/58/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/35/"
##   ..$ created   : chr "2014-12-20T18:44:01.103000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.486000Z"
##   ..$ url       : chr "http://swapi.co/api/people/78/"
##  $ :List of 16
##   ..$ name      : chr "Grievous"
##   ..$ height    : chr "216"
##   ..$ mass      : chr "159"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "brown, white"
##   ..$ eye_color : chr "green, yellow"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/59/"
##   ..$ films     : chr "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/36/"
##   ..$ vehicles  : chr "http://swapi.co/api/vehicles/60/"
##   ..$ starships : chr "http://swapi.co/api/starships/74/"
##   ..$ created   : chr "2014-12-20T19:43:53.348000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.488000Z"
##   ..$ url       : chr "http://swapi.co/api/people/79/"
##  $ :List of 14
##   ..$ name      : chr "Tarfful"
##   ..$ height    : chr "234"
##   ..$ mass      : chr "136"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "brown"
##   ..$ eye_color : chr "blue"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/14/"
##   ..$ films     : chr "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/3/"
##   ..$ created   : chr "2014-12-20T19:46:34.209000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.491000Z"
##   ..$ url       : chr "http://swapi.co/api/people/80/"
##  $ :List of 14
##   ..$ name      : chr "Raymus Antilles"
##   ..$ height    : chr "188"
##   ..$ mass      : chr "79"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/2/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/6/" "http://swapi.co/api/films/1/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2014-12-20T19:49:35.583000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.493000Z"
##   ..$ url       : chr "http://swapi.co/api/people/81/"
##  $ :List of 13
##   ..$ name      : chr "Sly Moore"
##   ..$ height    : chr "178"
##   ..$ mass      : chr "48"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "pale"
##   ..$ eye_color : chr "white"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/60/"
##   ..$ films     : chr [1:2] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/6/"
##   ..$ created   : chr "2014-12-20T20:18:37.619000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.496000Z"
##   ..$ url       : chr "http://swapi.co/api/people/82/"
##  $ :List of 14
##   ..$ name      : chr "Tion Medon"
##   ..$ height    : chr "206"
##   ..$ mass      : chr "80"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "grey"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/12/"
##   ..$ films     : chr "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/37/"
##   ..$ created   : chr "2014-12-20T20:35:04.260000Z"
##   ..$ edited    : chr "2014-12-20T21:17:50.498000Z"
##   ..$ url       : chr "http://swapi.co/api/people/83/"
##  $ :List of 14
##   ..$ name      : chr "Finn"
##   ..$ height    : chr "unknown"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "black"
##   ..$ skin_color: chr "dark"
##   ..$ eye_color : chr "dark"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/7/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2015-04-17T06:52:40.793621Z"
##   ..$ edited    : chr "2015-04-17T06:52:40.793674Z"
##   ..$ url       : chr "http://swapi.co/api/people/84/"
##  $ :List of 14
##   ..$ name      : chr "Rey"
##   ..$ height    : chr "unknown"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "hazel"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/7/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ created   : chr "2015-04-17T06:54:01.495077Z"
##   ..$ edited    : chr "2015-04-17T06:54:01.495128Z"
##   ..$ url       : chr "http://swapi.co/api/people/85/"
##  $ :List of 15
##   ..$ name      : chr "Poe Dameron"
##   ..$ height    : chr "unknown"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "male"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/7/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr "http://swapi.co/api/starships/77/"
##   ..$ created   : chr "2015-04-17T06:55:21.622786Z"
##   ..$ edited    : chr "2015-04-17T06:55:21.622835Z"
##   ..$ url       : chr "http://swapi.co/api/people/86/"
##  $ :List of 14
##   ..$ name      : chr "BB8"
##   ..$ height    : chr "unknown"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "none"
##   ..$ skin_color: chr "none"
##   ..$ eye_color : chr "black"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "none"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/7/"
##   ..$ species   : chr "http://swapi.co/api/species/2/"
##   ..$ created   : chr "2015-04-17T06:57:38.061346Z"
##   ..$ edited    : chr "2015-04-17T06:57:38.061453Z"
##   ..$ url       : chr "http://swapi.co/api/people/87/"
##  $ :List of 13
##   ..$ name      : chr "Captain Phasma"
##   ..$ height    : chr "unknown"
##   ..$ mass      : chr "unknown"
##   ..$ hair_color: chr "unknown"
##   ..$ skin_color: chr "unknown"
##   ..$ eye_color : chr "unknown"
##   ..$ birth_year: chr "unknown"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/28/"
##   ..$ films     : chr "http://swapi.co/api/films/7/"
##   ..$ created   : chr "2015-10-13T10:35:39.229823Z"
##   ..$ edited    : chr "2015-10-13T10:35:39.229894Z"
##   ..$ url       : chr "http://swapi.co/api/people/88/"
##  $ :List of 15
##   ..$ name      : chr "Padmé Amidala"
##   ..$ height    : chr "165"
##   ..$ mass      : chr "45"
##   ..$ hair_color: chr "brown"
##   ..$ skin_color: chr "light"
##   ..$ eye_color : chr "brown"
##   ..$ birth_year: chr "46BBY"
##   ..$ gender    : chr "female"
##   ..$ homeworld : chr "http://swapi.co/api/planets/8/"
##   ..$ films     : chr [1:3] "http://swapi.co/api/films/5/" "http://swapi.co/api/films/4/" "http://swapi.co/api/films/6/"
##   ..$ species   : chr "http://swapi.co/api/species/1/"
##   ..$ starships : chr [1:3] "http://swapi.co/api/starships/49/" "http://swapi.co/api/starships/64/" "http://swapi.co/api/starships/39/"
##   ..$ created   : chr "2014-12-19T17:28:26.926000Z"
##   ..$ edited    : chr "2016-04-20T17:06:31.502555Z"
##   ..$ url       : chr "http://swapi.co/api/people/35/"
```
]

---
class: middle
count: false

# Acknowledgments

---

## Acknowledgments

Above materials are derived in part from the following sources:

* Hadley Wickham - [Adv-R Functionals](http://adv-r.had.co.nz/Functionals.html)

* Hadley Wickham - [R for Data Science](http://r4ds.had.co.nz/)

* Neil Saunders - [A brief introduction to "apply" in R](http://nsaunders.wordpress.com/2010/08/20/a-brief-introduction-to-apply-in-r/)

* Jenny Bryan - [Purrr Tutorial](https://jennybc.github.io/purrr-tutorial/)

* [R Language Definition](http://stat.ethz.ch/R-manual/R-devel/doc/manual/R-lang.html)