stri_detect {stringi}

Detect Pattern Occurrences

Description

These functions determine, for each string in str, if there is at least one match to a corresponding pattern.

Usage

stri_detect(str, ..., regex, fixed, coll, charclass)

stri_detect_fixed(
  str,
  pattern,
  negate = FALSE,
  max_count = -1,
  ...,
  opts_fixed = NULL
)

stri_detect_charclass(str, pattern, negate = FALSE, max_count = -1)

stri_detect_coll(
  str,
  pattern,
  negate = FALSE,
  max_count = -1,
  ...,
  opts_collator = NULL
)

stri_detect_regex(
  str,
  pattern,
  negate = FALSE,
  max_count = -1,
  ...,
  opts_regex = NULL
)

Arguments

str

character vector; strings to search in

...

supplementary arguments passed to the underlying functions, including additional settings for opts_collator, opts_regex, opts_fixed, and so on

pattern, regex, fixed, coll, charclass

character vector; search patterns; for more details refer to stringi-search

negate

single logical value; whether a no-match to a pattern is rather of interest

max_count

single integer; allows to stop searching once a given number of occurrences is detected; -1 (the default) inspects all elements

opts_collator, opts_fixed, opts_regex

a named list used to tune up the search engine's settings; see stri_opts_collator, stri_opts_fixed, and stri_opts_regex, respectively; NULL for the defaults

Details

Vectorized over str and pattern (with recycling of the elements in the shorter vector if necessary). This allows to, for instance, search for one pattern in each given string, search for each pattern in one given string, and search for the i-th pattern within the i-th string.

If pattern is empty, then the result is NA and a warning is generated.

stri_detect is a convenience function. It calls either stri_detect_regex, stri_detect_fixed, stri_detect_coll, or stri_detect_charclass, depending on the argument used.

See also stri_startswith and stri_endswith for testing whether a string starts or ends with a match to a given pattern. Moreover, see stri_subset for a character vector subsetting.

If max_count is negative, then all stings are examined. Otherwise, searching terminates once max_count matches (or, if negate is TRUE, no-matches) are detected. The uninspected cases are marked as missing in the return vector. Be aware that, unless pattern is a singleton, the elements in str might be inspected in a non-consecutive order.

Value

Each function returns a logical 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_detect: about_search, stri_startswith()

Examples

stri_detect_fixed(c('stringi R', 'R STRINGI', '123'), c('i', 'R', '0'))
stri_detect_fixed(c('stringi R', 'R STRINGI', '123'), 'R')

stri_detect_charclass(c('stRRRingi','R STRINGI', '123'),
   c('\\p{Ll}', '\\p{Lu}', '\\p{Zs}'))

stri_detect_regex(c('stringi R', 'R STRINGI', '123'), 'R.')
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), '[[:alpha:]]*?')
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), '[a-zC1]')
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), '( R|RE)')
stri_detect_regex('stringi', 'STRING.', case_insensitive=TRUE)

stri_detect_regex(c('abc', 'def', '123', 'ghi', '456', '789', 'jkl'),
   '^[0-9]+$', max_count=1)
stri_detect_regex(c('abc', 'def', '123', 'ghi', '456', '789', 'jkl'),
   '^[0-9]+$', max_count=2)
stri_detect_regex(c('abc', 'def', '123', 'ghi', '456', '789', 'jkl'),
   '^[0-9]+$', negate=TRUE, max_count=3)