Data 607 Week 03

Chapter 8 - Problem 03

Packages installation

First, we will install the stringr package to convert a string to a vector.

library(stringr)

Loading Data

raw.data <- "555-1239Moe Szyslak(636) 555-0113Burns, C. Montgomery555-6542Rev. Timothy Lovejoy555 8904Ned Flanders636-555-3226Simpson, Homer5543642Dr. Julius Hibbert"
#From textbook. Extracts names only.
unformatted_name <- unlist(str_extract_all(raw.data, "[[:alpha:]., ]{2,}"))
unformatted_name

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

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

formatted_name <- str_replace_all(unformatted_name, '([:graph:]+?), ([:print:]+)', '\\2 \\1')
formatted_name

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

table1 <- data.frame(unformatted_name,formatted_name)
table1

##       unformatted_name       formatted_name
## 1          Moe Szyslak          Moe Szyslak
## 2 Burns, C. Montgomery  C. Montgomery Burns
## 3 Rev. Timothy Lovejoy Rev. Timothy Lovejoy
## 4         Ned Flanders         Ned Flanders
## 5       Simpson, Homer        Homer Simpson
## 6   Dr. Julius Hibbert   Dr. Julius Hibbert

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

with_title <- str_detect(formatted_name, "[[:alpha:]]{2,3}[.]")
table2 <- data.frame(formatted_name,with_title)
table2

##         formatted_name with_title
## 1          Moe Szyslak      FALSE
## 2  C. Montgomery Burns      FALSE
## 3 Rev. Timothy Lovejoy       TRUE
## 4         Ned Flanders      FALSE
## 5        Homer Simpson      FALSE
## 6   Dr. Julius Hibbert       TRUE

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

with_second_name <- str_detect(unformatted_name," [A-z]{1}\\. ")
table3 <- data.frame(unformatted_name,with_second_name)
table3

##       unformatted_name with_second_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

Chapter 8 - Problem 04

Describe the types of strings that conform to the following regular expressions and construct an example that is matched by the regular expression.

[0-9]+\$

#This matches the vector containing strings with continuous numbers followed by a dollar sign at the end. As example:

mixed <- c("How many zeros in 1000000000000000$?")
extracted <- str_match(mixed, '[0-9]+\\$')
extracted

##      [,1]               
## [1,] "1000000000000000$"

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

#This matches the vector containing strings with one to four continuous lowercase letters surrounded by word edges. As example:
mixed <- c("I am so happy that you showed up. Thank you so much!")
unlist(str_extract_all(mixed, '\\b[a-z]{1,4}\\b'))

## [1] "am"   "so"   "that" "you"  "up"   "you"  "so"   "much"

.*?\.txt$

#This matches the vector containing the entirety of any string that concludes with the four characters ‘.txt’. 
mixed <- c("this is not a file.txt", "but this is a file.txt", "this is .txt file")
unlist(str_extract_all(mixed, ".*?\\.txt$"))

## [1] "this is not a file.txt" "but this is a file.txt"

\d{2}/\d{2}/\d{4}

#This matches the vector containing strings that have a pattern of two digits, a forward slash, another two digits, another forward slash, and then four more digits.
mixed <- c("12/10/1988 12/100/1988 120/10/1988")
unlist(str_extract_all(mixed, "\\d{2}/\\d{2}/\\d{4}"))

## [1] "12/10/1988" "20/10/1988"

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

#This matches the vectors containing strings closed by ending and corresponding closing tags.
exampleE <- c("<head><bold>Testing</bold></>", "<body>Testing 1 2 3...</body>")
unlist(str_extract_all(exampleE, "<(.+?)>.+?</\\1>"))

## [1] "<bold>Testing</bold>"          "<body>Testing 1 2 3...</body>"

Chapter 8 - Problem 09

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.

secret_code <- 'clcopCow1zmstc0d87wnkig7OvdicpNuggvhryn92Gjuwczi8hqrfpRxs5Aj5dwpn0TanwoUwisdij7Lj8kpf03AT5Idr3coc0bt7yczjatOaootj55t3Nj3ne6c4Sfek.r1w1YwwojigOd6vrfUrbz2.2bkAnbhzgv4R9i05zEcrop.wAgnb.SqoU65fPa1otfb7wEm24k6t3sR9zqe5fy89n6Nd5t9kc4fE905gmc4Rgxo5nhDk!gr'
message_found <- unlist(str_extract_all(secret_code, "[[:upper:].!]{1,}"))
message_found

##  [1] "C"  "O"  "N"  "G"  "R"  "A"  "T"  "U"  "L"  "AT" "I"  "O"  "N"  "S" 
## [15] "."  "Y"  "O"  "U"  "."  "A"  "R"  "E"  "."  "A"  ".S" "U"  "P"  "E" 
## [29] "R"  "N"  "E"  "R"  "D"  "!"

message_found <- str_replace_all(paste(message_found, collapse = ''), "[.]", " ")
message_found

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