Searches for approximate matches to pattern (the first argument)
within each element of the string x (the second argument) using
the generalized Levenshtein edit distance (the minimal possibly
weighted number of insertions, deletions and substitutions needed to
transform one string into another).
agrep(pattern, x, max.distance = 0.1, costs = NULL,
ignore.case = FALSE, value = FALSE, fixed = TRUE,
useBytes = FALSE)agrepl(pattern, x, max.distance = 0.1, costs = NULL,
ignore.case = FALSE, fixed = TRUE, 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. Expressed either as integer, or as a fraction of the pattern length times the maximal transformation cost (will be replaced by the smallest integer not less than the corresponding fraction), or a list with possible components
cost:maximum number/fraction of match cost (generalized Levenshtein distance)
all:maximal number/fraction of all transformations (insertions, deletions and substitutions)
insertions:maximum number/fraction of insertions
deletions:maximum number/fraction of deletions
substitutions:maximum number/fraction of substitutions
If cost is not given, all defaults to 10%, and the
other transformation number bounds default to all.
The component names can be abbreviated.
a numeric vector or list with names partially matching
insertions, deletions and substitutions giving
the respective costs for computing the generalized Levenshtein
distance, or NULL (default) indicating using unit cost for
all three possible transformations.
Coerced to integer via as.integer if possible.
if FALSE, the pattern matching is case
sensitive and if TRUE, case is ignored during matching.
if FALSE, a vector containing the (integer)
indices of the matches determined is returned and if TRUE, a
vector containing the matching elements themselves is returned.
logical. If TRUE (default), the pattern is
matched literally (as is). Otherwise, it is matched as a regular
expression.
logical. in a multibyte locale, should the comparison be character-by-character (the default) or byte-by-byte.
agrep returns a vector giving the indices of the elements that
yielded a match, or, if value is TRUE, the matched
elements (after coercion, preserving names but no other attributes).
agrepl returns a logical vector.
The Levenshtein edit distance is used as measure of approximateness: it is the (possibly cost-weighted) total number of insertions, deletions and substitutions required to transform one string into another.
This uses tre by Ville Laurikari
(http://laurikari.net/tre/), which supports MBCS
character matching.
The main effect of useBytes is to avoid errors/warnings about
invalid inputs and spurious matches in multibyte locales.
It inhibits the conversion of inputs with marked encodings, and is
forced if any input is found which is marked as "bytes" (see
Encoding).
grep, adist.
A different interface to approximate string matching is provided by
aregexec().
# NOT RUN {
agrep("lasy", "1 lazy 2")
agrep("lasy", c(" 1 lazy 2", "1 lasy 2"), max = list(sub = 0))
agrep("laysy", c("1 lazy", "1", "1 LAZY"), max = 2)
agrep("laysy", c("1 lazy", "1", "1 LAZY"), max = 2, value = TRUE)
agrep("laysy", c("1 lazy", "1", "1 LAZY"), max = 2, ignore.case = TRUE)
# }
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