Write first letters of all words from a string into a new one

Question

I have to write all first letters of a string with 9 words in a new string. Is there a better way to do it than:

    eg <- "This is a test I developed"
    temp.eg <- strsplit(eg,' ')[[1]]
    temp.eg <- substr(temp.eg, 0, 1)
    new.eg <- paste(temp.eg, collapse = "")

Also, is there another way of splitting the string, so I dont have to use:

strsplit() [[1]]

Your solution looks good to me. What do you mean with "is there a better way"? — KenHBS, May 18 '17 at 09:27
Possible duplicate of http://stackoverflow.com/questions/9721052/r-extract-part-of-string — akrun, May 18 '17 at 09:42

Cath · Answer 1 · 2017-05-18T11:46:26.150

You can use gsub to extract the first letter and words boundary (\\b):

gsub("\\b(\\w)(\\b|(\\w+))( |$)", "\\1", eg)
[1] "TiatId"

Explanation: you're asking for a "word" character (\\w) that comes after a word boundary and that is followed by either a word boundary or more word character then either a space or the end of the string ($).

Another option given by @lukeA:

gsub("(?<!\\b).|\\s", "", eg, perl=TRUE)
[1] "TiatId"

It uses look-behind (?<!: before must not be...) to "suppress" (replace by empty string) anything or a space which follows anything that is not a word boundary.

score 3 · Answer 2 · answered May 18 '17 at 09:38

To avoid [[ subset we can use unlist, the rest of your code looks fine:

paste(substr(unlist(strsplit(eg, " ")), 1, 1), collapse = "")
# [1] "TiatId"

If we have more than one string:

egLong <- c("This is a test I developed", "another test me")

sapply(strsplit(egLong, " "), function(i){
  paste(substr(i, 1, 1), collapse = "")
  })
# [1] "TiatId" "atm"

Write first letters of all words from a string into a new one

2 Answers2