Genesis Middleton Data 607 Professor Catlin SP 2023

Introduction

The coding in this document is being done to gain familiarity with manipulating strings by first using a dataset obtained from fivethirtyeight and retrieving majors using specific keywords, as well as using expressions to identify patterns within strings as a form of filtering.

Import

library(tidyverse)

## ── Attaching packages ─────────────────────────────────────── tidyverse 1.3.2 ──
## ✔ ggplot2 3.3.6     ✔ purrr   0.3.4
## ✔ tibble  3.1.7     ✔ dplyr   1.0.9
## ✔ tidyr   1.2.0     ✔ stringr 1.4.0
## ✔ readr   2.1.2     ✔ forcats 0.5.1
## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag()    masks stats::lag()

library(RCurl)

## 
## Attaching package: 'RCurl'
## 
## The following object is masked from 'package:tidyr':
## 
##     complete

x <- getURL("https://raw.githubusercontent.com/fivethirtyeight/data/master/college-majors/majors-list.csv")
data <- read.csv(text = x)

Question 1

provide code that identifies the majors that contain either “DATA” or “STATISTICS”

datastats_majors <- data %>%
  filter(str_detect(data$Major, "DATA") | str_detect(data$Major, "STATISTICS"))

datastats_majors

##   FOD1P                                         Major          Major_Category
## 1  6212 MANAGEMENT INFORMATION SYSTEMS AND STATISTICS                Business
## 2  2101      COMPUTER PROGRAMMING AND DATA PROCESSING Computers & Mathematics
## 3  3702               STATISTICS AND DECISION SCIENCE Computers & Mathematics

Question 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”) The two exercises below are taken from R for Data Science, 14.3.5.1 in the on-line version:

Fruits <- c('[1] "bell pepper"  "bilberry"     "blackberry"   "blood orange"
[5] "blueberry"    "cantaloupe"   "chili pepper" "cloudberry"  
[9] "elderberry"   "lime"         "lychee"       "mulberry"    
[13] "olive"        "salal berry"')

Fruits <- str_extract_all(Fruits, "\\w[a-z]+\\s?[a-z]+\\w")
unlist(Fruits)

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

Question 3

3 Describe, in words, what these expressions will match: • (.)\1\1 • “(.)(.)\2\1” • (..)\1 • “(.).\1.\1” • “(.)(.)(.).*\3\2\1”

(.)\1\1 The expression (.)\1\1 will match any three charcters in a row that are the same. Here, the (.) indicates the first character that potential mathes should reference to. The following \1 represets the second charcter that should match the intial character, and same goes for the third character where the \1 still indicates reference to the first character.

This expression will match the strings “aaa”, “bbb”, “ccc” where each string follows the formula.

“(.)(.)\2\1” The expression “(.)(.)\2\1” reveals that two characters are used in the first and second position of a string that then requires the third and fourth characters to reflect its characters

The strings “abba”, “wzwz”, “raak” all match the expression.

(..)\1 The expression (..)\1 matches any two characters followed by two more characters that rects the first group. some example of potential strings to match the expressions include: “aabb”, “jiij”, “zyzy”

“(.).\1.\1” The expression “(.).\1.\1” matches any string where the third and fith characters reflects the first caracter while 2nd and 4th characters are independent. To reiterat, the (.) represents the character the rest of the string will reference to in one way or another. the . represents independent characters that do not need to reference to any part of the string. Lastly, like the \1, the \1 represents the the requirment of to mirror the first character. Examples of this expression is “kakik”, “arama”, “wnwow”

“(.)(.)(.).\3\2\1” This last expression ”(.)(.)(.).\3\2\1” is used to match string whos first three characters are rever in the last three characters this random charcaters able to fill the middle. Strings that match this expressions conditions are “dreaerd”, “braplarb”, “aplrtlpa”.

Question 4

Construct regular expressions to match words that: Start and end with the same character. Contain a repeated pair of letters (e.g. “church” contains “ch” repeated twice.) Contain one letter repeated in at least three places (e.g. “eleven” contains three “e”s.)

library(stringr)

#Start and end with the same character.

animal_strings <- c("reindeer", "bear", "wolf", "eagle")
strext_animal <- str_extract_all(animal_strings, "^(.).*\\1$")
strext_animal

## [[1]]
## [1] "reindeer"
## 
## [[2]]
## character(0)
## 
## [[3]]
## character(0)
## 
## [[4]]
## [1] "eagle"

#Contain a repeated pair of letters (e.g. "church" contains "ch" repeated twice.)
strings_ext <- c("church", "table", "banana", "city" )
strings_ext2 <- str_extract_all(strings_ext, ".*(..).*\\1.*")
strings_ext2 

## [[1]]
## [1] "church"
## 
## [[2]]
## character(0)
## 
## [[3]]
## [1] "banana"
## 
## [[4]]
## character(0)

#Contain one letter repeated in at least three places (e.g. "eleven" contains three "e"s.)

triple_char <- c("pepper", "backpack", "bubble", "duck")
str_extract_all(triple_char, ".*(.).*\\1.*\\1.*")

## [[1]]
## [1] "pepper"
## 
## [[2]]
## character(0)
## 
## [[3]]
## [1] "bubble"
## 
## [[4]]
## character(0)