jidt/demos/python/example5TeBinaryMultivarTra...

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##
## Java Information Dynamics Toolkit (JIDT)
## Copyright (C) 2012, Joseph T. Lizier
##
## 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 3 of the License, 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 for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program. If not, see <http://www.gnu.org/licenses/>.
##
# = Example 5 - Multivariate transfer entropy on binary data =
# Multivariate transfer entropy (TE) calculation on binary data using the discrete TE calculator:
from jpype import *
import random
from operator import xor
# Change location of jar to match yours:
jarLocation = "../../infodynamics.jar"
# Start the JVM (add the "-Xmx" option with say 1024M if you get crashes due to not enough memory space)
startJVM(getDefaultJVMPath(), "-ea", "-Djava.class.path=" + jarLocation)
# Generate some random binary data.
numObservations = 100
sourceArray = [[random.randint(0,1) for y in xrange(2)] for x in xrange(numObservations)] # for 10 rows (time-steps) for 2 variables
sourceArray2= [[random.randint(0,1) for y in xrange(2)] for x in xrange(numObservations)] # for 10 rows (time-steps) for 2 variables
# Destination variable takes a copy of the first bit of the source in bit 1,
# and an XOR of the two bits of the source in bit 2:
destArray = [[0, 0]]
for j in range(1,numObservations):
destArray.append([sourceArray[j-1][0], xor(sourceArray[j-1][0], sourceArray[j-1][1])])
# Create a TE calculator and run it:
teCalcClass = JPackage("infodynamics.measures.discrete").TransferEntropyCalculator
teCalc = teCalcClass(4,1)
teCalc.initialise()
# We need to construct the joint values of the dest and source before we pass them in,
# and need to use the matrix conversion routine when calling from Matlab/Octave:
mUtils= JPackage('infodynamics.utils').MatrixUtils
teCalc.addObservations(mUtils.computeCombinedValues(sourceArray, 2), \
mUtils.computeCombinedValues(destArray, 2))
result = teCalc.computeAverageLocalOfObservations()
print('For source which the 2 bits are determined from, result should be close to 2 bits : %.3f' % result)
teCalc.initialise()
teCalc.addObservations(mUtils.computeCombinedValues(sourceArray2, 2), \
mUtils.computeCombinedValues(destArray, 2))
result2 = teCalc.computeAverageLocalOfObservations()
print('For random source, result should be close to 0 bits in theory: %.3f' % result2)
print('The result for random source is inflated towards 0.3 due to finite observation length (%d). One can verify that the answer is consistent with that from a random source by checking: teCalc.computeSignificance(1000); ans.pValue\n' % teCalc.getNumObservations())