Splitting

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1. Split up a string like “apples, pears, and bananas” into individual components.

x <- c("apples, pears, and bananas")
str_split(x, ", +(and +)?")[[1]]

[1] "apples"  "pears"   "bananas"

Exercise 2. Why is it better to split up by boundary("word") than " "?

Splitting by boundary("word") is a more sophisticated method to split a string into words. It recognizes non-space punctuation that splits words, and also removes punctuation while retaining internal non-letter characters that are parts of the word, e.g., “can’t” See the ICU website for a description of the set of rules that are used to determine word boundaries.

Consider this sentence from the official Unicode Report on word boundaries,

sentence <- "The quick (“brown”) fox can’t jump 32.3 feet, right?"

Splitting the string on spaces considers will group the punctuation with the words,

str_split(sentence, " ")

[[1]]
[1] "The"       "quick"     "(“brown”)" "fox"       "can’t"     "jump"      "32.3"     
[8] "feet,"     "right?"   

However, splitting the string using boundary("word") correctly removes punctuation, while not separating “32.2” and “can’t”,

str_split(sentence, boundary("word"))

[[1]]
[1] "The"   "quick" "brown" "fox"   "can’t" "jump"  "32.3"  "feet"  "right"

3. What does splitting with an empty string ("") do? Experiment, and then read the documentation.

str_split("ab. cd|agt", "")[[1]]

 [1] "a" "b" "." " " "c" "d" "|" "a" "g" "t"

It splits the string into individual characters.