| stri_startswith {stringi} | R Documentation |
These functions check if a string starts or ends with a match to a given pattern. Also, it is possible to check if there is a match at a specific position.
stri_startswith(str, ..., fixed, coll, charclass) stri_endswith(str, ..., fixed, coll, charclass) stri_startswith_fixed(str, pattern, from = 1L, ..., opts_fixed = NULL) stri_endswith_fixed(str, pattern, to = -1L, ..., opts_fixed = NULL) stri_startswith_charclass(str, pattern, from = 1L) stri_endswith_charclass(str, pattern, to = -1L) stri_startswith_coll(str, pattern, from = 1L, ..., opts_collator = NULL) stri_endswith_coll(str, pattern, to = -1L, ..., opts_collator = NULL)
str |
character vector |
... |
supplementary arguments passed to the underlying functions,
including additional settings for |
pattern, fixed, coll, charclass |
character vector defining search patterns; for more details refer to stringi-search |
from |
integer vector |
to |
integer vector |
opts_collator, opts_fixed |
a named list used to tune up
the search engine's settings; see |
Vectorized over str, pattern,
and from or to (with recycling
of the elements in the shorter vector if necessary).
If pattern is empty, then the result is NA
and a warning is generated.
Argument start controls the start position in str
where there is a match to a pattern.
to gives the end position.
Indexes given by from or to are of course 1-based,
i.e., an index 1 denotes the first character
in a string. This gives a typical R look-and-feel.
For negative indexes in from or to, counting starts
at the end of the string. For instance, index -1 denotes the last code point
in the string.
If you wish to test for a pattern match at an arbitrary
position in str, use stri_detect.
stri_startswith and stri_endswith are convenience functions.
They call either stri_*_fixed, stri_*_coll,
or stri_*_charclass, depending on the argument used.
Relying on these underlying functions directly will make your code run
slightly faster.
Note that testing for a pattern match at the start or end of a string
has not been implemented separately for regex patterns.
For that you may use the "^" and "$" meta-characters,
see stringi-search-regex.
Each function returns a logical vector.
Other search_detect:
stri_detect(),
stringi-search
stri_startswith_charclass(" trim me! ", "\\p{WSpace}")
stri_startswith_fixed(c("a1", "a2", "b3", "a4", "c5"), "a")
stri_detect_regex(c("a1", "a2", "b3", "a4", "c5"), "^a")
stri_startswith_fixed("ababa", "ba")
stri_startswith_fixed("ababa", "ba", from=2)
stri_startswith_coll(c("a1", "A2", "b3", "A4", "C5"), "a", strength=1)
pat <- stri_paste("\u0635\u0644\u0649 \u0627\u0644\u0644\u0647 ",
"\u0639\u0644\u064a\u0647 \u0648\u0633\u0644\u0645XYZ")
stri_endswith_coll("\ufdfa\ufdfa\ufdfaXYZ", pat, strength=1)