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

## 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
}