stri_detect: Detect a Pattern Match

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

Value

Each function returns a logical vector.

Details

Vectorized over str and pattern.

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 un-inspected 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.

Examples

Run this code

# NOT RUN {
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)

# }