Assignment 3: R Character Manipulation and Date Processing

Please deliver links to an R Markdown file (in GitHub and rpubs.com) with solutions to the problems below. You may work in a small group, but please submit separately with names of all group participants in your submission.

1. Provide code that identifies the majors that contain either “DATA” or “STATISTICS”

Using the 173 majors listed in fivethirtyeight.com’s College Majors dataset [https://fivethirtyeight.com/features/the-economic-guide-to-picking-a-college-major/]

majors_df = read.csv('https://raw.githubusercontent.com/fivethirtyeight/data/master/college-majors/recent-grads.csv', header = TRUE)

Create a pattern that identifies the major containing either “DATA” or “STATISTICS”

pattern <- "(DATA|STATISTICS)"
matches <- grep(pattern, majors_df$Major, value = TRUE, ignore.case = TRUE)
matches

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

2 Write code that transforms the data below:

[1] “bell pepper” “bilberry” “blackberry” “blood orange”

[5] “blueberry” “cantaloupe” “chili pepper” “cloudberry”

[9] “elderberry” “lime” “lychee” “mulberry”

[13] “olive” “salal berry”

Into a format like this:

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

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

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

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

[13] "olive"        "salal berry"'

transformed_data <- scan(text = raw_data, what = "character", quiet = TRUE, quote = "\"")
transformed_data <- transformed_data[!grepl("^\\[", transformed_data)]

print(transformed_data)

##  [1] "bell pepper"  "bilberry"     "blackberry"   "blood orange" "blueberry"   
##  [6] "cantaloupe"   "chili pepper" "cloudberry"   "elderberry"   "lime"        
## [11] "lychee"       "mulberry"     "olive"        "salal berry"

The two exercises below are taken from R for Data Science:

3 Describe, in words, what these expressions will match:

• (.)\1\1

This regular expression consists of three parts: (.): The first part is a capturing group that matches any single character and captures it. \1: The second part is a backreference to the first capturing group. It matches the same character as captured by the first group. \1: The third part is another backreference to the first capturing group, matching the same character again. This regular expression will match three consecutive identical characters.

• (.)(.)\2\1

This regular expression consists of four parts: (.): The first part is a capturing group that matches any single character and captures it. (.): The second part is another capturing group that matches any single character and captures it. \2: This is a backreference to the second capturing group, matching the character captured by the second group. \1: This is a backreference to the first capturing group, matching the character captured by the first group. This regular expression will match two consecutive characters that are the same.

• (..)\1

This regular expression consists of two parts: (..): The first part is a capturing group that matches any two consecutive characters and captures them. \1: The second part is a backreference to the first capturing group, matching the same two characters as captured by the first group. This regular expression will match two consecutive identical pairs of characters.

• (.).\1.\1

This regular expression consists of three parts: (.): The first part is a capturing group that matches any single character and captures it. \1: This is a backreference to the first capturing group, matching the character captured by the first group. \1: This is another backreference to the first capturing group, matching the same character again. This regular expression will match a single character surrounded by two identical characters.

• (.)(.)(.).*\3\2\1

This regular expression consists of five parts: (.): The first part is a capturing group that matches any single character and captures it. (.): The second part is another capturing group that matches any single character and captures it. (.): The third part is yet another capturing group that matches any single character and captures it. .*: This part matches zero or more characters (any character sequence). \3\2\1: This part is a sequence of backreferences to the capturing groups, matching the characters captured by the third, second, and first groups in that order. This regular expression will match a sequence of characters where the last three characters are in reverse order compared to the first three characters.

4 Construct regular expressions to match words that:

Start and end with the same character:

reg1 = "^(.).+\\1"

Contain a repeated pair of letters:

reg2 = "\\b\\w*(\\w{2})\\w*\\1"

Contain one letter repeated in at least three places:

reg3 = "^[a-z]*([a-z])\\1[a-z]*"