DATA 607 - Week 3 Assignment

Problems

3. Copy the introductory example. The vector names stores the extracted names.

# Introductory text

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

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.

# Because we have two formats: First Last and Last, First
#   the first name is either a word terminated by a space (including 
#   a single initial with a period) or
#   a word at the end of the string.

first <- str_trim(str_extract(name,"(\\w+ )|(\\w{1}\\. )?+(\\w+$)"))

first

## [1] "Moe"           "C. Montgomery" "Timothy"       "Ned"          
## [5] "Homer"         "Julius"

# So, the last name is either the word before the comma or
#   the word at the end of the string

last <- str_extract(name,"(\\w+,)|(\\w+$)")

last

## [1] "Szyslak"  "Burns,"   "Lovejoy"  "Flanders" "Simpson," "Hibbert"

# Now we can combine into one vector
firstLast <- str_c(first," ",last)

firstLast

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

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

# For a title, we look for 2 or more letters and a period

title <- str_detect(name,"\\w{2,}\\.")

title

## [1] FALSE FALSE  TRUE FALSE FALSE  TRUE

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

# To locate whether someone has a second name, we look for a period in the
#   first name from the initial

twoNames <- str_detect(first,"\\.")

twoNames

## [1] FALSE  TRUE FALSE FALSE FALSE FALSE

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

1. [0-9]+\\$

   This pattern matches one or more digits between 0 and 9 and a dollar sign. One example that would match: “129$”

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

   This pattern matches words that are any combination of 1,2,3, or 4 lower-case letters. An example of a match here would be “adam”

3. .*?\\.txt$

   Text that matches this pattern would contain any character (or no characters!) with the string “.txt” at the end. The text “filename.txt” would be matched by this, for example.

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

   This pattern matches 2 digits, a slash, 2 more digits, another slash, and 4 digits. This matches date strings such as “11/30/2017”.

5. <(.+?)>.+?</\\1>

   This regex matches HTML tags such as “ Row Title

   " since it looks for angle brackets with any characters inside, characters after that, and the same angle-bracket text with a / added to the beginning (closing tag).

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