---
title: "Lab 3"
subtitle: "Statistical Computing & Programming"
author: ""
institute: ""
date: "06-02-20"
output:
  xaringan::moon_reader:
    css: "slides.css"
    lib_dir: libs
    nature:
      highlightStyle: github
      highlightLines: true
      countIncrementalSlides: false
editor_options: 
  chunk_output_type: console
---

```{r include=FALSE}
knitr::opts_chunk$set(echo = TRUE, message = FALSE, warning = TRUE,
                      comment = "#>", highlight = TRUE,
                      fig.align = "center")
```

## Getting started

- Navigate to your private team repo, `lab3-[github_team]`

<br/>

- Open an RStudio (Pawn or Rook) session; then go to
    - `File` > `New Project`
    - select `Version Control`
    - select `Git`
    - paste the repository URL - available at your GitHub 
      repo `lab3-[github_team]` when you click `Clone or download` and then
      `Clone with HTTPS`
    - Click `Create Project`
    
<br/>

- Since this is a team-based lab, consider using branches.

<br/><br/>

<i>
You may do this on your local machine if you have git configured with 
R/RStudio. 
</i>

---

## Package `rvest`

`rvest` is a package authored by Hadley Wickham that makes basic processing and 
manipulation of HTML data easy.

```{r}
library(rvest)
```

Core functions:

| Function            | Description                                                       |
|---------------------|-------------------------------------------------------------------|
| `xml2::read_html()` | read HTML from a character string or connection                   |
| `html_nodes()`      | select specified nodes from the HTML document using CSS selectors |
| `html_table()`      | parse an HTML table into a data frame                             |
| `html_text()`       | extract tag pairs' content                                        |
| `html_name()`       | extract tags' names                                               |
| `html_attrs()`      | extract all of each tag's attributes                              |
| `html_attr()`       | extract tags' attribute value by name                             |

---

## Today's objectives

- Follow along as the TA gets you started with web scraping and brief overview
  of [SelectorGadget](https://selectorgadget.com/).

- Complete Lab 3 (24 hours to submit this team-based lab)

    - Work with those in your group in a breakout room
    - Grade is for effort and completion
    - This lab will be helpful for Homework 3
    - Challenge yourself to create a spatial visualization for the data
      you scrape