Assignment 3

knitr::opts_chunk$set(eval = TRUE, message = FALSE, warning = FALSE)
library(readr)
library(dplyr)
library(tidyverse)
library(knitr)
url <- "https://raw.githubusercontent.com/fivethirtyeight/data/master/college-majors/majors-list.csv"
majors <- read_csv(url)

#1 Find all majors that contain the word “Data” or “Statistics”

data_or_stat <- majors[grepl("DATA|STATISTICS", majors$Major, ignore.case = TRUE), ]
data_or_stat$Major

## [1] "MANAGEMENT INFORMATION SYSTEMS AND STATISTICS"
## [2] "COMPUTER PROGRAMMING AND DATA PROCESSING"     
## [3] "STATISTICS AND DECISION SCIENCE"

#2 Transform The data

text <- '[1] "bell pepper"  "bilberry"     "blackberry"   "blood orange"

[5] "blueberry"    "cantaloupe"   "chili pepper" "cloudberry"  

[9] "elderberry"   "lime"         "lychee"       "mulberry"    

[13] "olive"        "salal berry"'

text <- gsub("\\s{2,}", "", text)
text_no_ws = gsub('[^a-z" ]', '', text)
text_comma = gsub('""', '", "', text_no_ws)
text_comma = substring(gsub('" "', '", "', text_comma), 2)
text_formatted <- paste0('c(', text_comma, ')')
cat(text_formatted)

## c("bell pepper", "bilberry", "blackberry", "blood orange", "blueberry", "cantaloupe", "chili pepper", "cloudberry", "elderberry", "lime", "lychee", "mulberry", "olive", "salal berry")

#3 Explain the regex

(.)\1\1: This regex would match a string of 3 of the same character. For instance it would match ‘zzz’ or ‘…’.
“(.)(.)\2\1”: This regex would match a 4 character string which are a palindrome. For instance it would match on ‘xyyx’ or ‘7;;7’.
(..)\1: This regex would match any 4 characters where the first 2 characters and second 2 characters match. For instance it would match ‘abab’ or ‘2.2.’.
“(.).\1.\1”: This regex would match a 5 character string where the 1st, 3rd, and 5th character are the same character, and the 2nd and 4th can be any character. For instance it would match ‘acaba’ or ‘5:5m5’.
“(.)(.)(.).*\3\2\1”: Would match a string of any length 6 characters or greater where the first 3 characters are repeated backwards as the last 3 characters. For instance it would match on ‘abcn71’;.,cba’ or ‘123abc321’.

#4 Construct regular expressions to match words that:

Start and end with the same character: (.).*\1
Contain a repeated pair of letters (e.g. “church” contains “ch” repeated twice.): .*(..).*\1.*
Contain one letter repeated in at least three places (e.g. “eleven” contains three e”s.): “.*(.).*\1.*\1.*