Partial Matching of Character Strings
DESCRIPTION:
Returns a vector of the indices of target that are partially matched by input.
USAGE: 
charmatch(input, target, nomatch=NA)
REQUIRED ARGUMENTS:
input:
vector of character strings to match.
target:
vector of target character strings to match against.
OPTIONAL ARGUMENTS:
nomatch:
the value to be returned when a string in input does not partially match any string in target.
VALUE:
an integer vector like input containing the index of target that partially matches input. If none of the elements of target match, nomatch is returned. If it is an ambiguous match, a 0 is returned.
DETAILS:
This function is useful for processing the arguments to functions. It is very similar to the pmatch function. However, pmatch does not allow a distinction between no match and an ambiguous match. The pmatch function doesnt allow a match to the empty string, while charmatch does.
SEE ALSO:
pmatch , amatch , grep , match .
EXAMPLES: 
charmatch("mea", c("mean", "median", "mode")) # returns 1


charmatch("m", c("mean", "median", "mode")) # returns 0
pmatch("m", c("mean", "median", "mode")) # returns NA


charmatch(c("sin", "cot"), c("cos", "sin", "tan"), nomatch = -1)
        # returns c(2, -1)


charmatch("","") # returns 1
pmatch("","") # returns NA