R/Matrix.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.



## provide some interfaces to our C implementations


## t in Matrix is now faster
##setMethod("t", signature(x = "ngCMatrix"),
##    function(x) .Call(R_transpose_ngCMatrix, x))

## overloading of [ for ngCMatrix cannot be accomplished
## easily as there are too many signatures to overload.


## density for ngC/dgCMatrix 
.density_Matrix <- function(x) length(x@i)/prod(dim(x))

## helper to convert names into an integer index
.translate_index <- function(i, labels, n) {
  
  ## checking is deferred to the actual subsetting code
  if(is.logical(i)) return(which(i))
  
  if(is.numeric(i)) {
    ## deal with neg. and 0's
    if(all(i>0)) return(as.integer(i))
    else return(seq(n)[i])
  }
  
  ## if no labels were specified we used "1", "2", etc.
  if(is.null(labels)) labels <- seq(n)
  sel <- structure(seq(length(labels)), names = labels)[i]
  
  if(any(is.na(sel))) stop("subscript out of bounds")
  sel
}



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