Ahmad Mousavi

Ahmad Mousavi

Assistant Prof. of Data Science,
Dept. of Math. and Stat.,
American University

Lab 9: Strings and Regex

DATA 412/612 · Week 9 · PDF · Source (.qmd)

Build a quote from pieces, then write a few patterns.

Work in a Quarto document. Do 9.1 and 9.2 first. words comes with stringr.

library(tidyverse)

1. Pieces and replacement

  1. From full <- "To be or not to be, that is the question.", use str_sub() to pull two pieces and str_c() to join them so writeLines() prints a two-line quote.
  2. Replace "back" and "lack" with "foo" in one call. Run it on c("back", "lack") and on c("back", "lack", "black").

2. Regular expressions

Use words. For each item, print the matching words.

  1. Four-letter words that start with a.
  2. Words that start with a vowel.
  3. Words that end in ed but not eed.
  4. Words that start with three consonants.
  5. Words that end in a consonant.
  6. Words that end in ing or ise.
  7. Words with two or more vowel-consonant pairs in a row ([aeiou][^aeiou] twice).