R/fade.R

In rEMM: Extensible Markov Model for Modelling Temporal Relationships Between Clusters

#######################################################################
# rEMM - Extensible Markov Model (EMM) for Data Stream Clustering in R
# Copyright (C) 2011 Michael Hahsler
#
# 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.


## build uses its own implementation of fade! See build.R

.fade <- function(x, t = 1, lambda = NULL) {
  if (is.null(lambda))
    lambda_factor <- x@tnn_d$lambda_factor
  else
    lambda_factor <- 2 ^ (-lambda)

  ## fade counts (tNN)
  x@tnn_d$counts <- x@tnn_d$counts * lambda_factor ^ t

  ## fade transition counts (TRACDS)
  x@tracds_d$mm <- smc_fade(x@tracds_d$mm, lambda_factor ^ t)

  invisible(x)
}


setMethod("fade", signature(x = "EMM", t = "numeric", lambda = "missing"),
  function(x, t, lambda)
    .fade(x, t))

setMethod("fade", signature(x = "EMM", t = "missing", lambda = "missing"),
  function(x, t, lambda)
    .fade(x, t = 1))

setMethod("fade", signature(x = "EMM", t = "numeric", lambda = "numeric"),
  function(x, t, lambda)
    .fade(x, t, lambda))

setMethod("fade", signature(x = "EMM", t = "missing", lambda = "numeric"),
  function(x, t, lambda)
    .fade(x, , lambda))