Problem 3

(A)

load the raw data into R

raw.data <-"555-1239Moe Szyslak(636) 555-0113Burns, C. Montgomery555-6542Rev. Timothy Lovejoy555 8904Ned Flanders636-555-3226Simpson, Homer5553642Dr. Julius Hibbert"
raw.data
## [1] "555-1239Moe Szyslak(636) 555-0113Burns, C. Montgomery555-6542Rev. Timothy Lovejoy555 8904Ned Flanders636-555-3226Simpson, Homer5553642Dr. Julius Hibbert"

we use stringr library for data manipulation

library(stringr)

looking for alphabetic characters, also contain period,commas and empty spaces, and add a quantifier that at least length two.

name <- unlist(str_extract_all(raw.data, "[[:alpha:]., ]{2,}"))
name
## [1] "Moe Szyslak"          "Burns, C. Montgomery" "Rev. Timothy Lovejoy"
## [4] "Ned Flanders"         "Simpson, Homer"       "Dr. Julius Hibbert"

(B)

find any character text from 2 to 3 character follow by “.”

title<-str_detect(name,"[\\w]{2,3}\\. ")
cbind(name,title)
##      name                   title  
## [1,] "Moe Szyslak"          "FALSE"
## [2,] "Burns, C. Montgomery" "FALSE"
## [3,] "Rev. Timothy Lovejoy" "TRUE" 
## [4,] "Ned Flanders"         "FALSE"
## [5,] "Simpson, Homer"       "FALSE"
## [6,] "Dr. Julius Hibbert"   "TRUE"

(C)

sec_name = str_detect(name,"\\s[A-z]\\. ")
cbind(name,sec_name)
##      name                   sec_name
## [1,] "Moe Szyslak"          "FALSE" 
## [2,] "Burns, C. Montgomery" "TRUE"  
## [3,] "Rev. Timothy Lovejoy" "FALSE" 
## [4,] "Ned Flanders"         "FALSE" 
## [5,] "Simpson, Homer"       "FALSE" 
## [6,] "Dr. Julius Hibbert"   "FALSE"

Question 4

(A)[0-9]+\$

One or more digit numbber and follow by “$”sign

sample1 = 'abc123$123'
a<-str_extract_all(sample1,'[0-9]+\\$')
a
## [[1]]
## [1] "123$"

(B)\b[a-z]{1,4}\b

word edge and charater letter with length 1 to 4 and word edge

example2 = 'abcde abc'
str_extract_all(example2,"\\b[a-z]{1,4}\\b")
## [[1]]
## [1] "abc"

(C).?\.txt$ Start with any character, means zero or more time, ? means optional or one times, a period,txt at the end.

example3 ='.local.txt'
str_extract_all(example3,".*?\\.txt$")
## [[1]]
## [1] ".local.txt"

(D)\d{2}/\d{2}/\d{4}

Any digital with length2/any digital with length 2/ any digital with length of 4.

example4= '02/17/2019'
str_extract_all(example4,"\\d{2}/\\d{2}/\\d{4}")
## [[1]]
## [1] "02/17/2019"

(E)<(.+?)>.+?</\1>

‘ any character ’

example5 = '<any>anything</any>'
str_extract_all(example5,"<(.+?)>.+?</\\1>")
## [[1]]
## [1] "<any>anything</any>"