patternapply

Iteratively try patterns against a character vector.
git clone https://git.eamoncaddigan.net/patternapply.git
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countPatternMatches.R (812B)

      1 #' Count how many matches are generated by each pattern.
      2 #' 
      3 #' @param X A character vector where matches are sought.
      4 #' @param patterns A vector of regular expression patterns.
      5 #'   
      6 #' @return A integer vector of same length as \code{patterns} with a count of 
      7 #'   matches.
      8 #'   
      9 #' @details This is meant to be useful when developing a vector of regexes to 
     10 #'   apply to text. Unlike \code{patternappy()}, which only finds the first 
     11 #'   regex that matches each element of text, a text element here can match 
     12 #'   multiple regexes. Therefore, the sum of the returned vector may not equal 
     13 #'   the length of the input \code{X}.
     14 #' @export
     15 countPatternMatches <- function(X, patterns) {
     16   return(vapply(patterns, 
     17                 function(pattern) length(grep(pattern, X)), 
     18                 integer(1)))
     19 }