def factorProduct(f1, f2, mnCards):
"""
Multiply two factors by finding same variable assignments and multiplying their phi together.
"""
# Get the unique variables across both factors
uniqueVars = f2.variables[:]
for i in range(len(f1.variables)):
if f1.variables[i] not in uniqueVars:
uniqueVars.insert(0, f1.variables[i])
# Create the new product factor
factor = Factor(uniqueVars)
for i in range(len(factor.variables)):
factor.setCard(i, mnCards[factor.variables[i]])
factor.calculateStrides()
j, k = 0, 0
psi = []
assignment = [0 for i in range(len(factor.variables))]
factorSize = 1
# Size of new factor will be product of each variable's cardinality
for i in range(len(factor.card)):
factorSize *= factor.card[i]
for i in range(factorSize):
if debug: print "multiplying", j, k, f1.phi[j], f2.phi[k]
psi.append(f1.phi[j] * f2.phi[k])
# Loop from last to first since values are 000, 001, 010, 011 instead of 000, 100, 010, 110
for v in range(len(factor.variables)-1,-1,-1):
curVariable = factor.variables[v]
assignment[v] += 1
if assignment[v] == factor.card[v]:
assignment[v] = 0
if curVariable in f1.variables:
j = j - (factor.card[v] - 1) * f1.stride[f1.variables.index(curVariable)]
if curVariable in f2.variables:
k = k - (factor.card[v] - 1) * f2.stride[f2.variables.index(curVariable)]
else:
if curVariable in f1.variables:
j = j + f1.stride[f1.variables.index(curVariable)]
if curVariable in f2.variables:
k = k + f2.stride[f2.variables.index(curVariable)]
break
factor.phi = psi[:]
return factor
def readFunctionTables(mnCards, mnCliques):
"""
Reads function tables defined in the input file
"""
mnFactors = []
factorIndex, factorNum = 0, 0
fClass = Factor(mnCliques[factorIndex])
for i in range(len(fClass.variables)):
fClass.setCard(i, mnCards[fClass.variables[i]])
fClass.calculateStrides()
factor = []
done = False
while not done:
inputRow = inFile.readline().strip()
if inputRow == "":
continue
else:
if " " in inputRow:
splitRow = inputRow.split()
if factorNum == 0:
factorNum = int(splitRow[0])
for i in range(1, len(splitRow)):
factor.append(float(splitRow[i]))
else:
for i in range(len(splitRow)):
factor.append(float(splitRow[i]))
if factorNum == len(factor):
factorNum = 0
fClass.phi = factor
mnFactors.append(fClass)
factor = []
factorIndex += 1
if factorIndex < len(mnCliques):
fClass = Factor(mnCliques[factorIndex])
for i in range(len(fClass.variables)):
fClass.setCard(i, mnCards[fClass.variables[i]])
fClass.calculateStrides()
else:
factorNum = int(inputRow)
if len(mnFactors) >= len(mnCliques):
# We have read in all the cliques so break out of while loop
done = True
return mnFactors
