# -*- coding: iso-8859-1 -*-## This file is a part of the Bayes Blocks library## Copyright (C) 2001-2006 Markus Harva, Antti Honkela, Alexander# Ilin, Tapani Raiko, Harri Valpola and Tomas 謘tman.## 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, or (at your option)# 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 (included in file License.txt in the# program package) for more details.## $Id: DecayCounters.py 5 2006-10-26 09:44:54Z ah $#import Netimport mathclass LinearDecayCounter:    """Decay counter with linearly increasing memory length."""    def __init__(self, net, ratio = 0.5):        self.samples = 1.0        self.ratio = ratio        self.cumsum = 0.0        self.decay = 0.0        self.pythoncounter = Net.PythonDecayCounter(self.DoDecay)        net.SetDecayCounter(self.pythoncounter)    def Reinstall(self, net):        self.pythoncounter = Net.PythonDecayCounter(self.DoDecay)        net.SetDecayCounter(self.pythoncounter)    def DoDecay(self):        self.samples += 1        self.cumsum += 1        x = (self.samples * self.ratio - 1) / self.cumsum        if (x < 0.99):            x = math.exp(x-1)        self.cumsum *= x        self.decay = x        return float(x)class SaturatingDecayCounter:    """Decay counter with constant decay."""    def __init__(self, net, limit = 100):        assert limit > 1        self.samples = 1.0        self.cumsum = 0.0        self.decay = 0.0        self.limit = limit        self.pythoncounter = Net.PythonDecayCounter(self.DoDecay)        net.SetDecayCounter(self.pythoncounter)    def Reinstall(self, net):        self.pythoncounter = Net.PythonDecayCounter(self.DoDecay)        net.SetDecayCounter(self.pythoncounter)    def DoDecay(self):        self.samples += 1        self.cumsum += 1        x = (self.limit - 2) / (self.limit - 1)        self.cumsum *= x        self.decay = x        return float(x)class FunctionalDecayCounter:    def __init__(self, net, memfunc, memparams = ()):        self.samples = 1        self.cumsum = 0.0        self.decay = 0.0        self.memfunc = memfunc        if type(memparams) != type(()):            memparams = (memparams, )        self.memparams = memparams        self.oldmem = 0.0        self.pythoncounter = Net.PythonDecayCounter(self.DoDecay)        net.SetDecayCounter(self.pythoncounter)    def Reinstall(self, net):        self.pythoncounter = Net.PythonDecayCounter(self.DoDecay)        net.SetDecayCounter(self.pythoncounter)    def DoDecay(self):        self.samples += 1        self.cumsum += 1        memlen = self.memfunc(self.samples - 1, *self.memparams)        #if memlen > (self.oldmem + 1):        #    raise ValueError("DecayCounter memory length increase > 1")        x = memlen / self.cumsum        if x > 1:            print "DecayCounter evaluated decay > 1"            #raise ValueError("DecayCounter evaluated decay > 1")        self.oldmem = memlen        self.cumsum *= x        self.decay = x        return float(x)