charmatch                package:base                R Documentation

Partial String Matching

Description:

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

Usage:

     charmatch(x, table, nomatch = NA_integer_)

Arguments:

       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 (integer) value to be returned at non-matching positions.

Details:

     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"'.

Value:

     An integer vector of the same length as 'x', giving the indices of
     the elements in 'table' which matched, or 'nomatch'.

Author(s):

     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.

Examples:

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

