stri_detect: 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
|
character vector; strings to search in |
|
supplementary arguments passed to the underlying functions, including additional settings for |
|
character vector; search patterns; for more details refer to stringi-search |
|
single logical value; whether a no-match to a pattern is rather of interest |
|
single integer; allows to stop searching once a given number of occurrences is detected; |
|
a named list used to tune up the search engine’s settings; see |
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.
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'))
## [1] TRUE TRUE FALSE
stri_detect_fixed(c('stringi R', 'R STRINGI', '123'), 'R')
## [1] TRUE TRUE FALSE
stri_detect_charclass(c('stRRRingi','R STRINGI', '123'),
c('\\p{Ll}', '\\p{Lu}', '\\p{Zs}'))
## [1] TRUE TRUE FALSE
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), 'R.')
## [1] FALSE TRUE FALSE
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), '[[:alpha:]]*?')
## [1] TRUE TRUE TRUE
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), '[a-zC1]')
## [1] TRUE FALSE TRUE
stri_detect_regex(c('stringi R', 'R STRINGI', '123'), '( R|RE)')
## [1] TRUE FALSE FALSE
stri_detect_regex('stringi', 'STRING.', case_insensitive=TRUE)
## [1] TRUE
stri_detect_regex(c('abc', 'def', '123', 'ghi', '456', '789', 'jkl'),
'^[0-9]+$', max_count=1)
## [1] FALSE FALSE TRUE NA NA NA NA
stri_detect_regex(c('abc', 'def', '123', 'ghi', '456', '789', 'jkl'),
'^[0-9]+$', max_count=2)
## [1] FALSE FALSE TRUE FALSE TRUE NA NA
stri_detect_regex(c('abc', 'def', '123', 'ghi', '456', '789', 'jkl'),
'^[0-9]+$', negate=TRUE, max_count=3)
## [1] TRUE TRUE FALSE TRUE NA NA NA