Shana Green

DATA 607 - Homework 3

Due Date: 9/12/2020

1. Using the 173 majors listed in fivethirtyeight.com’s College Majors dataset The Economic Guide To Picking A College Major, provide code that identifies the majors that contain either “DATA” or “STATISTICS”.

# Loading data sets for the college majors

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

grep(pattern = 'STATISTICS|DATA', majors$Major, value = TRUE, ignore.case = TRUE)

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

Two results produced STATISTICS and one with DATA.

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”)

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

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

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

[13] "olive"        "salal berry"'


fruitveggie

## [1] "[1] \"bell pepper\"  \"bilberry\"     \"blackberry\"   \"blood orange\"\n\n[5] \"blueberry\"    \"cantaloupe\"   \"chili pepper\" \"cloudberry\"  \n\n[9] \"elderberry\"   \"lime\"         \"lychee\"       \"mulberry\"    \n\n[13] \"olive\"        \"salal berry\""

#I created an empty vector of fruitveg and I split the elements using the strsplit function by removing the "\" string.

fruitveg<-vector()

splitfruitveggie <- strsplit(fruitveggie,"\"")[[1]]

fruitveg<-splitfruitveggie[c(FALSE,TRUE)]

fruitveg

##  [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, 14.3.5.1 in the on-line version:

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

(.)\1\1
"(.)(.)\\2\\1"
(..)\1
"(.).\\1.\\1"
"(.)(.)(.).*\\3\\2\\1" 

(.)\1\1 matches the same characters that appear three times in a row. For example, “bbb”.

“(.)(.)\2\1” matches a pair of characters, followed by the same pair in reverse order. For example, “cddc”

(..)\1 matches any two characters repeated. For example, “f6f6”.

“(.).\1.\1” matches a character, followed by any character, then the original, then any character, and finally the original character. For example, “abada”.

**"(.)(.)(.).*\3\2\1“** selects three characters, followed by zero or more characters produced in reversed order. For example,”hij6jih".

4. Construct regular expressions to match words that:

Start and end with the same character.

str_subset(words, "^(.)((.*\\1$|1?$)") 

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.)

str_subset(words, "([A-Za-z][A-Za-z]).*\\1")