Assignment 3

Exercise #1

There are 3 majors listed in this dataset that contain ‘DATA’ or ‘STATISTICS’.

These majors are:
* MANAGEMENT INFORMATION SYSTEMS AND STATISTICS
* COMPUTER PROGRAMMING AND DATA PROCESSING
* STATISTICS AND DECISION SCIENCE

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

majors <- read.csv(urlfile)

Code Option 1

data_stat_majors <- grep("DATA|STATISTICS",majors$Major,value=TRUE)
data_stat_majors

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

Code Option 2

data_stat_majors <- str_detect(majors$Major,"DATA|STATISTICS")
majors$Major[data_stat_majors]

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

Exercise #2

This is a trick question. The output of c() is a vector coerced to a common type; in the case provided, the input are strings, therefore the output will be a a character vector. The code we see above is how a character vector appears in the R console as output, where each string represents an element of the character vector. The numbering of the output indicates the index of the starting element - so 4 elements on first row, fifth element will start on 2nd row [5], 9th element starts on 3rd row [9], etc.

If you wanted to control the number of elements presented on each row, you can use cat() and specify argument fill to numeric value of print width

fruits_list<-cat(c("bell pepper", "bilberry", "blackberry", "blood orange", "blueberry", "cantaloupe", "chili pepper", "cloudberry", "elderberry", "lime", "lychee", "mulberry", "olive", "salal berry"),fill=45)

## bell pepper bilberry blackberry blood orange 
## blueberry cantaloupe chili pepper cloudberry 
## elderberry lime lychee mulberry olive 
## salal berry

Exercise #3

Note: escape characters were used in the rmarkdown of this assigment to escape special meaning for formatting.
Answers for pattern matching expressions can be read/referenced from how they appear in the html output on rpubs.

1. (.)\1\1 will match any string containing a character repeated 3x sequentially

2. “(.)(.)\\2\\1” will match a very short palindrome where 2nd character will repeat sequentially and be followed by repeat of 1st character (ex: abba)

3. (..)\1 will match sequentially repeating character pair (ex:chch)

4. “(.).\\1.\\1” will match strings that are length of 5 where a character repeats at 1st, 3rd, and 5th index (ex: bebab)

5. “(.)(.)(.).*\\3\\2\\1” will match strings that are at least 6 characters long where first 3 characters of string are also the last 3 characters in reverse order (ex: abcdcba)

Exercise #4

Note: escape characters were used in the rmarkdown of this assigment to escape special meaning for formatting.
Answers for pattern matching expressions can be read/referenced from how they appear in the html output on rpubs.

1. Start and end with the same character: ^(.).*\1$

2. Contain a repeated pair of letters (e.g. “church” contains “ch” repeated twice): (..).*\1

3. Contain one letter repeated in at least three places (e.g. “eleven” contains three “e”s.): (.).*\1.*\1