R strsplit keep last empty element as empty string

Question

R's strsplit drops the last element if "empty" (example 2) but not when occurring first (example 3) or in the middle of the vector to split (example 4).

> unlist(strsplit(x = "1,4", split = ",")) #Example 1
[1] "1" "4"
> unlist(strsplit(x = ",4", split = ",")) #Example 2
[1] ""  "4"
> unlist(strsplit(x = "1,", split = ",")) #Example 3
[1] "1"
> unlist(strsplit(x = "1,,,4", split = ",")) #Example 4
[1] "1" ""  ""  "4"

Is there a way to parse strings that allows keeping the last element if empty after split :

> strmagic(x = "1,", split = ",") #strmagic being the wanted function
[1] "1" ""

A solution with other packages is here (is seems). Can it be done in base R?

UPDATE

Will adding a filler element be necessary ed then a la:

strmagic <- function(v, sep)lapply(v, function(x)head(unlist(strsplit(paste(x, "-", sep = sep), split = sep)), -1))

You can add a `,` at the end of `x` when no comma ending the string but not really efficient, use `stringr` — Clemsang, Oct 01 '19 at 14:47

score 1 · Answer 1 · answered Oct 01 '19 at 15:07

Weird. This works but is not the most efficient. ZAQ is just a set of random characters

sp <- function( X ){
    X <- paste0( X, "ZAQ" )
    X <- unlist(strsplit(x = X, split = ","))
    X <- gsub( "ZAQ" ,"" ,X) 
    X
}
sp("1,4")
sp(",4")
sp("1,")
sp("1,,,4")

score -1 · Answer 2 · edited Mar 29 '23 at 14:30

-1

strmagic <- function(x) unlist(strsplit(sub(",$", ",,", x), split = ","))

strsplit does not recognize the "empty" last element. sub(",$", ",,", x) appends an additional comma to x if the last character in x is a comma, solving the problem.

edited Mar 29 '23 at 14:30

Mikael Jagan

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answered Dec 02 '22 at 03:36

racionais MC

1

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Do not post an answer with merely codes. While your solution can be useful, you should also explain why the code will fix the problem that was described in the question. – 4b0 Dec 02 '22 at 03:42

R strsplit keep last empty element as empty string

2 Answers2