MSDS Spring 2018

DATA 607 Data Aquisition and Management

Jiadi Li

Week 3 Assignment:R Character Manipulation and Date Processing

Chapter 8 3.Copy the introductory example. The vector name stores the extracted names.

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

library(stringr)
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"

1. Use the tools of this chapter to rearrange the vector so that all elements conform to the standard first_name last_name.

for (i in 1:length(name)) {
  if (str_detect(name[i],",")) {
    name_replace <- unlist(str_split(name[i],","))
    name[i] <- str_c(name_replace[2]," ",name_replace[1])
  }
}
name

## [1] "Moe Szyslak"          " C. Montgomery Burns" "Rev. Timothy Lovejoy"
## [4] "Ned Flanders"         " Homer Simpson"       "Dr. Julius Hibbert"

2. Construct a logical vector indicating whether a character has a title (i.e.,Rev. and Dr.).

title_list <- unlist(str_extract_all(name,"^[:alpha:]{2,}\\. "))
str_detect(name,title_list)

## [1] FALSE FALSE  TRUE FALSE FALSE  TRUE

3. Construct a logical vector indicating whether a character has a second name.

second_name <- unlist(str_extract_all(name,"[:print:]? [:alpha:]\\. "))
str_detect(name,second_name)

## [1] FALSE  TRUE FALSE FALSE FALSE FALSE

4.Describe the types of strings that conform to the following regular expressions and construct an example that is matched by the regular expression.
(a) [0-9]+\$
one or more digits followed by a dollar sign

example_a <- c("37281394$","5$")
str_detect(example_a,"[0-9]+\\$")

## [1] TRUE TRUE

2. \b[a-z]{1,4}\b
   one to four lower case letters only with nothing at the front or back

example_b <- c("agd","enjs")
str_detect(example_b,"\\b[a-z]{1,4}\\b")

## [1] TRUE TRUE

3. .*?\.txt$
   any number of any character followed by “.txt”

example_c <- c("dswer.txt","e.txt",".txt")
str_detect(example_c,".*?\\.txt$")

## [1] TRUE TRUE TRUE

4. \d{2}/\d{2}/\d{4}
   two digits followed by “/” followed by two digits followed by “/” followed by four digits. Normally used to show dates.

example_d <- c("02/18/2018","10/15/1993")
str_detect(example_d,"\\d{2}/\\d{2}/\\d{4}")

## [1] TRUE TRUE

5. <(.+?)>.+?</\1>
   any number of character within “< >” followed by any number of any character followed by any character (exactly same as the first group of character in < >) within “</>”

example_e <- c("<hello>world</hello>")
str_detect(example_e,"<(.+?)>.+?</\\1>")

## [1] TRUE

9.The following code hides a secret message. Crack it with R and regular expressions. Hint: Some of the characters are more revealing than others! The code snippet is also available in the materials at www.r-datacollection.com.

raw.data <- "clcopCow1zmstc0d87wnkig7OvdicpNuggvhryn92Gjuwczi8hqrfpRxs5Aj5dwpn0TanwoUwisdij7Lj8kpf03AT5Idr3coc0bt7yczjatOaootj55t3Nj3ne6c4Sfek.r1w1YwwojigOd6vrfUrbz2.2bkAnbhzgv4R9i05zEcrop.wAgnb.SqoU65fPa1otfb7wEm24k6t3sR9zqe5fy89n6Nd5t9kc4fE905gmc4Rgxo5nhDk!gr"
code <- str_replace_all(str_replace_all(raw.data,"[:lower:]?[:digit:]?",""),"\\."," ")
code

## [1] "CONGRATULATIONS YOU ARE A SUPERNERD!"