R/string.R

In caroline: A Collection of Database, Data Structure, Visualization, and Utility Functions for R

pad <- function(vect,np){
 x <- as.numeric(vect)
 vect <- as.character(vect)
 for(p in 10^(1:np)){
   vect[x<p] <- paste("0",vect[x<p],sep="")
 }
 vect
}


m <- function(pattern, vect, names="V", types="character", mismatch=NA, ...){
  matches <- regexpr(pattern , vect )
  n <- length(gregexpr("[^\\])",pattern)[[1]]) #how many groups (non literal perends) does this pattern have
  if(length(types) == 1 & n > 1)
    types <- rep(types, n)
  if(length(names) == 1 & n > 1)
    names <- paste(names,1:n)

  if(n != length(names) | n != length(types)){
    print("ERROR: the number of backreferences in 'pattern' must equal the length of the 'names' and 'types' vectors")
  }else{
    ret <- list() 
    for(i in 1:n){
      this.vect <- as.vector(rep(NA,length(vect), mode=types[i]))
      this.vect[matches > 0] <- as.vector(sub(paste("(.*)", pattern ,"(.*)",sep=""),paste("\\",i+1,sep=""), vect[matches > 0], ...), mode=types[i]) 
      ret[[names[i]]] <- this.vect
    }
    if(n == 1){
      ret <- as.vector(ret[[1]])
      if(!is.na(mismatch)){
       isnomatch <- is.na(ret)
       ret[isnomatch] <- vect[isnomatch]
      }
      return(ret)
    }else{
      return(as.data.frame(ret, stringsAsFactors=FALSE))
    }
  }
}