Announcements

  • Homework 0 is now posted in the Calendar section, for which I will do a quick demo of R Markdown.
  • If there are ever any minor notes I need to pass along after lecture is over, such as minor bugs I didn’t notice, I will always post them in the section titled After-Class Updates. For example, in Lec01 I added a note on the use of :: in PACKAGE_NAME::FUNCTION_NAME().
  • Go over solutions to Lec01.R, which are at the beginning of Lec02.R.

In-Class

  • Slides: An example involving R’s webscraping abilities to collect data
  • In-class exercise:
    • Packages to install: the rvest and XML packages
    • Code: Lec02.R

After-Class Updates

There seems to be some differences in how R reads in webscraped data between Windows and Mac. Windows users will have a problem with the wp_data$p_need_grant variable, which gets read as a character vector and not a numerical variable.

The solution is to replace lines 122-126 in Lec02.R from

wp_data <- wp_data %>%
  mutate(
    comp_fee = currency_to_numeric(comp_fee),
    ave_no_need_grant = currency_to_numeric(ave_no_need_grant)
  )

to

wp_data <- wp_data %>%
  mutate(
    comp_fee = currency_to_numeric(comp_fee),
    ave_no_need_grant = currency_to_numeric(ave_no_need_grant),
    p_need_grant = currency_to_numeric(ave_no_need_grant)
  )

i.e. use the currency_to_numeric() function to convert on p_need_grant as well. Lec02.R on GitHub has now been updated to reflect this change.