charmatch {base}R Documentation

Partial String Matching


charmatch seeks matches for the elements of its first argument among those of its second.


charmatch(x, table, nomatch = NA)


x the values to be matched: converted to a character vector by as.character.
table the values to be matched against: converted to a character vector.
nomatch the value to be returned at non-matching positions.


Exact matches are preferred to partial matches (those where the value to be matched has an exact match to the initial part of the target, but the target is longer).

If there is a single exact match or no exact match and a unique partial match then the index of the matching value is returned; if multiple exact or multiple partial matches are found then 0 is returned and if no match is found then nomatch is returned.

NA values are treated as the string constant "NA".


This function is based on a C function written by Terry Therneau.

See Also

pmatch, match.

grep or regexpr for more general (regexp) matching of strings.


charmatch("", "")                             # returns 1
charmatch("m",   c("mean", "median", "mode")) # returns 0
charmatch("med", c("mean", "median", "mode")) # returns 2

[Package base version 2.5.0 Index]