MRtable.R

multi.freq.table = function(data, sep="+", dropzero=FALSE, clean=TRUE) {
  ## 共選分析
  # Takes boolean multiple-response data and tabulates it according
  #   to the possible combinations of each variable.
  #
  # See: http://stackoverflow.com/q/11348391/1270695
  
  counts = data.frame(table(data))
  N = ncol(counts)
  counts$Combn = apply(counts[-N] == 1, 1, 
                       function(x) paste(names(counts[-N])[x],
                                         collapse=sep))
  if (isTRUE(dropzero)) {
    counts = counts[counts$Freq != 0, ]
  } else if (!isTRUE(dropzero)) {
    counts = counts
  }
  if (isTRUE(clean)) {
    counts = data.frame(Combn = counts$Combn, Freq = counts$Freq)
  } 
  counts
}