Lab-15: O Tiger-lily, I wish you could talk!

Introduction

‘Silence, every one of you!’ cried the Tiger-lily, waving itself passionately from side to side, and trembling with excitement. ‘They know I can’t get at them!’ it panted, bending its quivering head towards Alice, ‘or they wouldn’t dare to do it!’

‘Never mind!’ Alice said in a soothing tone, and stooping down to the daisies, who were just beginning again, she whispered, ‘If you don’t hold your tongues, I’ll pick you!’

• Through the Looking Glass. Chapter 2. Lewis Carroll

Often the data we want is not available readily in a form we can import into R. It may be available as part of a table on a webpage, or even on several webpages that require human interaction to navigate, view, and copy. These operations can be automated to a great extent ( based on the complexity of the website) and the resulting data neatly made available as a tibble in a R session.

We will learn about the rvest package to scrape data from static pages, and then the RSelenium package to obtain data from interactive websites.

Setting up the R packages

knitr::opts_chunk$set(message = FALSE)
library(tidyverse)

## ── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
## ✔ dplyr     1.1.4     ✔ readr     2.1.5
## ✔ forcats   1.0.0     ✔ stringr   1.5.1
## ✔ ggplot2   3.5.0     ✔ tibble    3.2.1
## ✔ lubridate 1.9.3     ✔ tidyr     1.3.1
## ✔ purrr     1.0.2     
## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag()    masks stats::lag()
## ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors

library(rvest)

## 
## Attaching package: 'rvest'
## 
## The following object is masked from 'package:readr':
## 
##     guess_encoding

library(RSelenium)

Conclusion

References

1. https://rsconnect.biostat.jhsph.edu/ocs-bp-youth-mental-health-interactive/#Basic_steps_of_web_scraping