How to remove all whitespace from a string?

In general, we want a solution that is vectorised, so here's a better test example:

whitespace <- " \t\n\r\v\f" # space, tab, newline,                             # carriage return, vertical tab, form feedx <- c(  " x y ",           # spaces before, after and in between  " \u2190 \u2192 ", # contains unicode chars  paste0(            # varied whitespace         whitespace,     "x",     whitespace,     "y",     whitespace,     collapse = ""  ),     NA                 # missing)## [1] " x y "                           ## [2] " ← → "                           ## [3] " \t\n\r\v\fx \t\n\r\v\fy \t\n\r\v\f"## [4] NA

The base R approach: gsub

gsub replaces all instances of a string (fixed = TRUE) or regular expression (fixed = FALSE, the default) with another string. To remove all spaces, use:

gsub(" ", "", x, fixed = TRUE)## [1] "xy"                            "←→"             ## [3] "\t\n\r\v\fx\t\n\r\v\fy\t\n\r\v\f" NA 

As DWin noted, in this case fixed = TRUE isn't necessary but provides slightly better performance since matching a fixed string is faster than matching a regular expression.

If you want to remove all types of whitespace, use:

gsub("[[:space:]]", "", x) # note the double square brackets## [1] "xy" "←→" "xy" NA gsub("\\s", "", x)         # same; note the double backslashlibrary(regex)gsub(space(), "", x)       # same

"[:space:]" is an R-specific regular expression group matching all space characters. \s is a language-independent regular-expression that does the same thing.

The stringr approach: str_replace_all and str_trim

stringr provides more human-readable wrappers around the base R functions (though as of Dec 2014, the development version has a branch built on top of stringi, mentioned below). The equivalents of the above commands, using [str_replace_all][3], are:

library(stringr)str_replace_all(x, fixed(" "), "")str_replace_all(x, space(), "")

stringr also has a str_trim function which removes only leading and trailing whitespace.

str_trim(x) ## [1] "x y"          "← →"          "x \t\n\r\v\fy" NA    str_trim(x, "left")    ## [1] "x y "                   "← → "    ## [3] "x \t\n\r\v\fy \t\n\r\v\f" NA     str_trim(x, "right")    ## [1] " x y"                   " ← →"    ## [3] " \t\n\r\v\fx \t\n\r\v\fy" NA      

The stringi approach: stri_replace_all_charclass and stri_trim

stringi is built upon the platform-independent ICU library, and has an extensive set of string manipulation functions. The equivalents of the above are:

library(stringi)stri_replace_all_fixed(x, " ", "")stri_replace_all_charclass(x, "\\p{WHITE_SPACE}", "")

Here "\\p{WHITE_SPACE}" is an alternate syntax for the set of Unicode code points considered to be whitespace, equivalent to "[[:space:]]", "\\s" and space(). For more complex regular expression replacements, there is also stri_replace_all_regex.

stringi also has trim functions.

stri_trim(x)stri_trim_both(x)    # samestri_trim(x, "left")stri_trim_left(x)    # samestri_trim(x, "right")  stri_trim_right(x)   # same

I just learned about the "stringr" package to remove white space from the beginning and end of a string with str_trim( , side="both") but it also has a replacement function so that:

a <- " xx yy 11 22 33 " str_replace_all(string=a, pattern=" ", repl="")[1] "xxyy112233"

Use [[:blank:]] to match any kind of horizontal white_space characters.

gsub("[[:blank:]]", "", " xx yy 11 22  33 ")# [1] "xxyy112233"