Determine positions of approximate string matches.
aregexec(pattern, text, max.distance = 0.1, costs = NULL,
ignore.case = FALSE, fixed = FALSE, useBytes = FALSE)
a non-empty character string or a character string
containing a regular expression (for fixed = FALSE
) to be
matched.
Coerced by as.character
to a string if possible.
character vector where matches are sought.
Coerced by as.character
to a character vector if
possible.
maximum distance allowed for a match.
See agrep
.
cost of transformations.
See agrep
.
a logical. If TRUE
, case is ignored for
computing the distances.
If TRUE
, the pattern is matched literally (as is).
Otherwise (default), it is matched as a regular expression.
a logical. If TRUE
comparisons are
byte-by-byte rather than character-by-character.
A list of the same length as text
, each element of which is
either \(-1\) if there is no match, or a sequence of integers with
the starting positions of the match and all substrings corresponding
to parenthesized subexpressions of pattern
, with attribute
"match.length"
an integer vector giving the lengths of the
matches (or \(-1\) for no match).
aregexec
provides a different interface to approximate string
matching than agrep
(along the lines of the interfaces
to exact string matching provided by regexec
and
grep
).
Note that by default, agrep
performs literal matches,
whereas aregexec
performs regular expression matches.
See agrep
and adist
for more information
about approximate string matching and distances.
Comparisons are byte-by-byte if pattern
or any element of
text
is marked as "bytes"
.
regmatches
for extracting the matched substrings.
# NOT RUN { ## Cf. the examples for agrep. x <- c("1 lazy", "1", "1 LAZY") aregexec("laysy", x, max.distance = 2) aregexec("(lay)(sy)", x, max.distance = 2) aregexec("(lay)(sy)", x, max.distance = 2, ignore.case = TRUE) m <- aregexec("(lay)(sy)", x, max.distance = 2) regmatches(x, m) # }