How to find the length of a string in R

374
votes

How to find the length of a string (number of characters in a string) without splitting it in R? I know how to find the length of a list but not of a string.

And what about Unicode strings? How do I find the length (in bytes) and the number of characters (runes, symbols) in a Unicode string?

Related Question:

6
rstringunicodestring-length
using evaluate() along with an anonymous function to return the last element of | the vector c(8, 4, 0). Your anonymous function should only take one argument which should | be a variable x. – uxi

6 Answers

458
votes

See ?nchar. For example:

> nchar("foo")
[1] 3
> set.seed(10)
> strn <- paste(sample(LETTERS, 10), collapse = "")
> strn
[1] "NHKPBEFTLY"
> nchar(strn)
[1] 10
72
votes

Use stringi package and stri_length function

> stri_length(c("ala ma kota","ABC",NA))
[1] 11  3 NA

Why? Because it is the FASTEST among presented solutions :)

require(microbenchmark)
require(stringi)
require(stringr)
x <- c(letters,NA,paste(sample(letters,2000,TRUE),collapse=" "))
microbenchmark(nchar(x),str_length(x),stri_length(x))
Unit: microseconds
           expr    min     lq  median      uq     max neval
       nchar(x) 11.868 12.776 13.1590 13.6475  41.815   100
  str_length(x) 30.715 33.159 33.6825 34.1360 173.400   100
 stri_length(x)  2.653  3.281  4.0495  4.5380  19.966   100

and also works fine with NA's

nchar(NA)
## [1] 2
stri_length(NA)
## [1] NA

EDIT 2021

NA argument is no longer valid if you are using latest R version.

27
votes

You could also use the stringr package:

library(stringr)
str_length("foo")
[1] 3
25
votes
nchar("STRING")

Check out this

9
votes

The keepNA = TRUE option prevents problems with NA

nchar(NA)
## [1] 2
nchar(NA, keepNA=TRUE)
## [1] NA
6
votes
nchar(YOURSTRING)

you may need to convert to a character vector first;

nchar(as.character(YOURSTRING))