1. Copy the introductory example. The vector name stores the extracted names.
library(stringr)
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.

First, I’ll separate those names that are already in this format from those that need to be re-arranged.

rightOrder <- c(name[1], name[3], name[4], name[6])
wrongOrder <- c(name[2], name[5])
wrongOrder
## [1] "Burns, C. Montgomery" "Simpson, Homer"

Now, we change the order of the names that are not in the correct order.

montgomery <- unlist(str_split(wrongOrder[1], ","))
montgomery
## [1] "Burns"          " C. Montgomery"
montgomery <- str_trim(montgomery)
montgomery
## [1] "Burns"         "C. Montgomery"
add1 <- str_c(montgomery[2], montgomery[1], sep=" ")
add1
## [1] "C. Montgomery Burns"
homer <- unlist(str_split(wrongOrder[2],","))
homer <- str_trim(homer)
add2 <- str_c(homer[2], homer[1], sep=" ")

Finally, we add these two corrected names to the vector that contains names with the right order.

rightOrder <- c(rightOrder, add1, add2)
rightOrder
## [1] "Moe Szyslak"          "Rev. Timothy Lovejoy" "Ned Flanders"        
## [4] "Dr. Julius Hibbert"   "C. Montgomery Burns"  "Homer Simpson"
  1. Construct a logical vector indicating whether a character has a title (i.e., Rev. and Dr.).
hasTitle <- str_detect(rightOrder, "[aA-zZ]{2,}\\.")
hasTitle
## [1] FALSE  TRUE FALSE  TRUE FALSE FALSE
  1. Construct a logical vector indicating whether a character has a second name.
hasSecondName <- str_detect(rightOrder, "[A-Z]{1}\\.")
hasSecondName
## [1] FALSE FALSE FALSE FALSE  TRUE FALSE
  1. 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]+\$ Strings that have a series of at least 1 integer followed by a dollar sign conform to this expression. Example: abc12847$a

  2. \b[a-z]{1,4}\b Strings that contain 1-4 consecutive lowercase letters conform to this expression. Example: abc

  3. .*?\.txt$ Strings that end in .txt conform to this expression. Example: ok.txt

  4. \d{2}/\d{2}/\d{4} Strings that have two digits, a forward slash, two more digits, another forward slash, and lastly 4 digits conform to this expression. These are dates. Example: 02/13/2019

  5. <(.+?)>.+?</\1> XML tags conform to this expression. This is a tag followed by text and ending in the same tag that it began with, except with a forward slash. Example: < address >This is correct syntax< / address >