How to find the length of a string in R

Question

How to find the length of a string (i.e., 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:

How to find the "real" number of characters in a Unicode string in R

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, Feb 04 '17 at 14:25

Gavin Simpson · Accepted Answer · 2012-06-21T09:18:44.250

489

See ?nchar. For example:

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

edited Jun 21 '12 at 09:18

answered Jun 21 '12 at 09:04

Gavin Simpson

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@hadley Indeed, or for that matter any character vector with one or more `NA`s. (Though this is documented to be so). – Gavin Simpson Mar 19 '14 at 16:19
7

Or use `stri_length` from `stringi` - it works fine with NA's and it is faster :) Check my post! – bartektartanus Apr 04 '14 at 16:37
6

As of 3.3.1 the base defaults are set to give `nchar(NA) ## [1] NA` : see [nchar RDocumentation](https://www.rdocumentation.org/packages/base/versions/3.3.1/topics/nchar) – leerssej Oct 11 '16 at 01:15
Can I use the same method for a Unicode string? (see update) – Igor Chubin Feb 26 '17 at 16:00
3

@IgorChubin you should ask this as a new question, not edit an almost 2-year old one. – Gavin Simpson Feb 26 '17 at 18:44
@GavinSimpson: Asked it here: http://stackoverflow.com/questions/42481827/ – Igor Chubin Feb 27 '17 at 09:18

bartektartanus · Answer 2 · 2021-03-23T11:51:54.483

76

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.

edited Mar 23 '21 at 11:51

answered Mar 14 '14 at 09:36

bartektartanus

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Thank you for the answer and for the great library (it is your library if I understood it right). What about Unicode strings? – Igor Chubin Feb 26 '17 at 16:02
1

Works fine too. Look at this example: `stri_length('\u0105')` length is one, but... `stri_numbytes('\u0105')` 2 bytes are used – bartektartanus May 13 '17 at 12:39
This should be updated because `nchar()` now has an argument accounts for NA's: `allowNA = FALSE` – Riley Finn Aug 01 '19 at 21:23
1

`nchar(NA)` now is `NA` - R 4.0.4 – Rafs Mar 22 '21 at 16:43
This answer is 7 years old ;) Thank you @Jabro, I've edited it and added info about NA. – bartektartanus Mar 23 '21 at 11:52

score 30 · Answer 3 · answered Jun 21 '12 at 09:18

30

You could also use the stringr package:

library(stringr)
str_length("foo")
[1] 3

answered Jun 21 '12 at 09:18

johannes

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score 28 · Answer 4 · answered Jun 21 '12 at 09:07

28

nchar("STRING")

Check out this

answered Jun 21 '12 at 09:07

sobingt

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score 13 · Answer 5 · answered Mar 09 '16 at 09:48

13

The keepNA = TRUE option prevents problems with NA

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

answered Mar 09 '16 at 09:48

Thomas Buhl

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As of 3.3.1 the base defaults are set to give `nchar(NA) ## [1] NA` : see [nchar RDocumentation](https://www.rdocumentation.org/packages/base/versions/3.3.1/topics/nchar) – leerssej Oct 11 '16 at 01:12

score 9 · Answer 6 · edited Feb 09 '13 at 20:40

9

nchar(YOURSTRING)

you may need to convert to a character vector first;

nchar(as.character(YOURSTRING))

edited Feb 09 '13 at 20:40

Julius Vainora

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answered Feb 09 '13 at 20:12

Jonathan

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With the exception of a factor input, the coercion is performed by `nchar`. For factor inputs, `nchar` will throw an error and hence you will need to do the conversion first as you show. – Gavin Simpson Mar 08 '13 at 16:07

How to find the length of a string in R

6 Answers6

EDIT 2021

Linked

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