stringr: modifiers – R documentation

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stringr

modifiers

Control matching behaviour with modifier functions.

Description

fixed: Compare literal bytes in the string. This is very fast, but not usually what you want for non-ASCII character sets.
coll: Compare strings respecting standard collation rules.
regex: The default. Uses ICU regular expressions.
boundary: Match boundaries between things.

Usage

fixed(pattern, ignore_case = FALSE)

coll(pattern, ignore_case = FALSE, locale = "en", ...)

regex(pattern, ignore_case = FALSE, multiline = FALSE,
  comments = FALSE, dotall = FALSE, ...)

boundary(type = c("character", "line_break", "sentence", "word"),
  skip_word_none = NA, ...)

Arguments

`pattern`	Pattern to modify behaviour.
`ignore_case`	Should case differences be ignored in the match?
`locale`	Locale to use for comparisons. See `stringi::stri_locale_list()` for all possible options. Defaults to "en" (English) to ensure that the default collation is consistent across platforms.
`...`	Other less frequently used arguments passed on to `stringi::stri_opts_collator()`, `stringi::stri_opts_regex()`, or `stringi::stri_opts_brkiter()`
`multiline`	If `TRUE`, `$` and `^` match the beginning and end of each line. If `FALSE`, the default, only match the start and end of the input.
`comments`	If `TRUE`, white space and comments beginning with `#` are ignored. Escape literal spaces with `\` .
`dotall`	If `TRUE`, `.` will also match line terminators.
`type`	Boundary type to detect. `character` Every character is a boundary. `line_break` Boundaries are places where it is acceptable to have a line break in the current locale. `sentence` The beginnings and ends of sentences are boundaries, using intelligent rules to avoid counting abbreviations (details). `word` The beginnings and ends of words are boundaries.
`skip_word_none`	Ignore "words" that don't contain any characters or numbers - i.e. punctuation. Default `NA` will skip such "words" only when splitting on `word` boundaries.

Examples

pattern <- "a.b"
strings <- c("abb", "a.b")
str_detect(strings, pattern)
str_detect(strings, fixed(pattern))
str_detect(strings, coll(pattern))

# coll() is useful for locale-aware case-insensitive matching
i <- c("I", "\u0130", "i")
i
str_detect(i, fixed("i", TRUE))
str_detect(i, coll("i", TRUE))
str_detect(i, coll("i", TRUE, locale = "tr"))

# Word boundaries
words <- c("These are   some words.")
str_count(words, boundary("word"))
str_split(words, " ")[[1]]
str_split(words, boundary("word"))[[1]]

# Regular expression variations
str_extract_all("The Cat in the Hat", "[a-z]+")
str_extract_all("The Cat in the Hat", regex("[a-z]+", TRUE))

str_extract_all("a\nb\nc", "^.")
str_extract_all("a\nb\nc", regex("^.", multiline = TRUE))

str_extract_all("a\nb\nc", "a.")
str_extract_all("a\nb\nc", regex("a.", dotall = TRUE))

stringr

Simple, Consistent Wrappers for Common String Operations

v1.4.0

GPL-2 | file LICENSE

Authors

Hadley Wickham [aut, cre, cph], RStudio [cph, fnd]

Initial release

modifiers

Description

Usage

Arguments

See Also

Examples

stringr

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