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# stri_trim: Trim Characters from the Left and/or Right Side of a String

## Description

These functions may be used, e.g., to remove unnecessary white-spaces from strings. Trimming ends at the first or starts at the last `pattern` match.

## Usage

    stri_trim_both(str, pattern = "\\P{Wspace}", negate = FALSE)

    stri_trim_left(str, pattern = "\\P{Wspace}", negate = FALSE)

    stri_trim_right(str, pattern = "\\P{Wspace}", negate = FALSE)

    stri_trim(
      str,
      side = c("both", "left", "right"),
      pattern = "\\P{Wspace}",
      negate = FALSE
    )

## Arguments

`str` | a character vector of strings to be trimmed
`pattern` | a single pattern, specifying the class of characters (see stringi-search-charclass) to to be preserved (if `negate` is `FALSE`; default) or trimmed (otherwise)
`negate` | either `TRUE` or `FALSE`; see `pattern`
`side` | character [`stri_trim` only]; defaults to `'both'`

## Details

Vectorized over `str` and `pattern`.

`stri_trim` is a convenience wrapper over `stri_trim_left` and `stri_trim_right`.

Contrary to many other string processing libraries, our trimming functions are universal. The class of characters to be retained or trimmed can be adjusted.

For replacing pattern matches with an arbitrary replacement string, see `stri_replace`.

Trimming can also be used where you would normally rely on regular expressions. For instance, you may get `'23.5'` out of `'total of 23.5 bitcoins'`.

For trimming white-spaces, please note the difference between Unicode binary property ‘`\p{Wspace}`’ (more universal) and general character category ‘`\p{Z}`’, see stringi-search-charclass.

## Value

All functions return a character vector.

## Author(s)

Marek Gagolewski and other contributors

## See Also

The official online manual of stringi at https://stringi.gagolewski.com/

Gagolewski M., stringi: Fast and portable character string processing in R, Journal of Statistical Software 103(2), 2022, 1-59, doi:10.18637/jss.v103.i02

Other search_replace: `about_search`, `stri_replace_all()`, `stri_replace_rstr()`

Other search_charclass: `about_search`, `about_search_charclass`

## Examples

    stri_trim_left('               aaa')
    ## [1] "aaa"
    stri_trim_right('r-project.org/', '\\P{P}')
    ## [1] "r-project.org"
    stri_trim_both(' Total of 23.5 bitcoins. ', '\\p{N}')
    ## [1] "23.5"
    stri_trim_both(' Total of 23.5 bitcoins. ', '\\P{N}', negate=TRUE)
    ## [1] "23.5"