R/addComplement.R

In arules: Mining Association Rules and Frequent Itemsets

#######################################################################
# arules - Mining Association Rules and Frequent Itemsets
# Copyright (C) 2011-2015 Michael Hahsler, Christian Buchta, 
#			Bettina Gruen and Kurt Hornik
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


setMethod("addComplement", signature(x = "transactions"),
  function(x, labels, complementLabels=NULL) {
    
    ### default names for complements
    if(is.null(complementLabels)) complementLabels <- paste("!", 
      labels, sep="")
    
    add <- sapply(labels, function(y) !(x %in% y))
    m <- as.matrix(add)
    colnames(m) <- complementLabels
    tr <- as(m, "transactions")
    
    merge(x, tr)
  })