def splitCritValue(self,
bags: Distribution,
totalNoInst: float = None,
numerator: float = None):
if totalNoInst is None and numerator is None:
numerator = self.oldEnt(bags) - self.newEnt(bags)
if Utils.equal(numerator, 0):
return float('inf')
denumerator = self.splitEnt(bags)
if Utils.equal(denumerator, 0):
return float('inf')
return denumerator / numerator
elif numerator is None:
res = 0
noUnkown = totalNoInst - bags.total()
if Utils.gr(bags.total(), 0):
for i in range(bags.numBags()):
res = res - self.lnFunc(bags.perBag(i))
res = res - self.lnFunc(noUnkown)
res = res + self.lnFunc(totalNoInst)
return res / math.log(2)
else:
denumerator = self.splitEnt(bags, totalNoInst)
if Utils.equal(denumerator, 0):
return 0
denumerator /= totalNoInst
return numerator / denumerator
def splitEnt(self, bags: Distribution, totalnoInst: float = None):
if totalnoInst is None:
return super().splitEnt(bags)
res = 0
noUnknown = totalnoInst - bags.total()
if Utils.gr(bags.total(), 0):
for i in range(bags.numBags()):
res = res - self.lnFunc(bags.perBag(i))
res = res - self.lnFunc(noUnknown)
res = res + self.lnFunc(totalnoInst)
return res / math.log(2)
def selectModel(self, data: Instances, test: Instances = None):
if test is not None:
return self.selectModel(data)
multiVal = True
averageInfoGain = validModels = 0
checkDistribution = Distribution(data)
noSplitModel = NoSplit(checkDistribution)
if Utils.gr(2*self.m_minNoObj, checkDistribution.total()) or \
Utils.equal(checkDistribution.total(), checkDistribution.perClass(checkDistribution.maxClass())):
return noSplitModel
if self.m_allData is not None:
for attr in data.enumerateAttributes():
if attr.isNumeric() or Utils.gr(
0.3 * self.m_allData.numInstances(), attr.numValues()):
multiVal = False
break
currentModel = [None] * data.numAttributes() #type:List[C45Split]
sumOfWeights = data.sumOfWeight()
for i in range(data.numAttributes()):
if i != data.classIndex():
currentModel[i] = C45Split(i, self.m_minNoObj, sumOfWeights,
self.m_useMDLcorrection)
currentModel[i].buildClassifer(data)
if currentModel[i].checkModel():
if self.m_allData is not None:
if data.attribute(i).isNumeric() or \
(multiVal or Utils.gr(0.3*self.m_allData.numInstances(), data.attribute(i).numValues())):
averageInfoGain = averageInfoGain + currentModel[
i].infoGain()
validModels += 1
else:
averageInfoGain = averageInfoGain + currentModel[
i].infoGain()
validModels += 1
else:
currentModel[i] = None
if validModels == 0:
return noSplitModel
averageInfoGain = averageInfoGain / validModels
minResult = 0
for i in range(data.numAttributes()):
if i != data.classIndex() and currentModel[i].checkModel():
if currentModel[i].infoGain() >= averageInfoGain-1e-3 and\
Utils.gr(currentModel[i].gainRatio(), minResult):
bestModel = currentModel[i]
minResult = currentModel[i].gainRatio()
if Utils.equal(minResult, 0):
return noSplitModel
bestModel.distribution().addInstWithUnknown(data, bestModel.attIndex())
if self.m_allData is not None and not self.m_doNotMakeSplitPointActualValue:
bestModel.setSplitPoint(self.m_allData)
return bestModel
def splitCritValue(self,bags:Distribution,totalNoInst:float=None,oldEnt:float=None):
if totalNoInst is None:
numerator=self.oldEnt(bags)-self.newEnt(bags)
if Utils.equal(numerator, 0):
return float("inf")
return bags.total()/numerator
else:
noUnknown=totalNoInst-bags.total()
unknowRate=noUnknown/totalNoInst
if oldEnt is not None:
numerator = oldEnt - self.newEnt(bags)
else:
numerator=self.oldEnt(bags)-self.newEnt(bags)
numerator=(1-unknowRate)*numerator
if Utils.equal(numerator, 0):
return 0
return numerator/bags.total()
class PruneableClassifierTree(ClassifierTree):
def __init__(self, toSelectLocModel: ModelSelection, pruneTree: bool,
num: int, cleanup: bool, seed: int):
super().__init__(toSelectLocModel)
self.pruneTheTree = pruneTree
self.numSets = num
self.m_cleanup = cleanup
self.m_seed = seed
def buildClassifier(self, data: Instances):
data = Instances(data)
data.deleteWithMissingClass()
data.stratify(self.numSets)
self.buildTree(
data.trainCV(self.numSets, self.numSets - 1, self.m_seed),
not self.m_cleanup, data.testCV(self.numSets, self.numSets - 1))
if self.pruneTheTree:
self.prune()
if self.m_cleanup:
self.cleanup(Instances(data, 0))
def getNewTree(self, data: Instances, test: Instances = None):
newTree = PruneableClassifierTree(self.m_toSelectModel,
self.pruneTheTree, self.numSets,
self.m_cleanup, self.m_seed)
newTree.buildTree(data, not self.m_cleanup, test)
return newTree
def buildTree(self,
data: Instances,
keepData: bool,
test: Instances = None):
if keepData:
self.m_train = data
self.m_isLeaf = False
self.m_isEmpty = False
self.m_sons = None
self.m_localModel = self.m_toSelectModel.selectModel(data, test)
self.m_test = Distribution(test, self.m_localModel)
if self.m_localModel.numSubsets() > 1:
localTrain = self.m_localModel.split(data)
localTest = self.m_localModel.split(test)
self.m_sons = []
for i in range(len(self.m_sons)):
self.m_sons.append(self.getNewTree(localTrain[i],
localTest[i]))
localTrain[i] = None
localTest[i] = None
else:
self.m_isLeaf = True
if Utils.equal(data.sumOfWeight(), 0):
self.m_isEmpty = True
def prune(self):
if not self.m_isLeaf:
for i in range(len(self.m_sons)):
self.son(i).prune()
if Utils.gr(self.errorsForTree(),
self.errorsForLeaf()) or Utils.equal(
self.errorsForTree(), self.errorsForLeaf()):
self.m_sons = None
self.m_isLeaf = None
self.m_localModel = NoSplit(self.localModel().distribution())
def errorsForTree(self):
errors = 0
if self.m_isLeaf:
return self.errorsForLeaf()
for i in range(len(self.m_sons)):
if Utils.equal(self.localModel().distribution().perBag(i), 0):
errors += self.m_test.perBag(i) - self.m_test.perClassPerBag(
i,
self.localModel().distribution().maxClass())
else:
errors += self.son(i).errorsForTree()
return errors
def errorsForLeaf(self):
return self.m_test.total() - self.m_test.perClass(
self.localModel().distribution().maxClass())
class C45Split(ClassifierSplitModel):
def __init__(self, attIndex: int, minNoObj: int, sumOfWeights: float,
useMDLcorrection: bool):
super().__init__()
self.m_distribution = None #type:Distribution
self.m_numSubsets = 0
self.m_attIndex = attIndex
self.m_minNoObj = minNoObj
self.m_sumOfWeights = sumOfWeights
self.m_useMDLcorrection = useMDLcorrection
self.m_splitPoint = float("inf")
self.m_infoGain = 0
self.m_gainRatio = 0
def buildClassifer(self, instances: Instances):
self.m_numSubsets = 0
self.m_splitPoint = float("inf")
self.m_infoGain = 0
self.m_gainRatio = 0
if instances.attribute(self.m_attIndex).isNominal():
self.m_complexityIndex = instances.attribute(
self.m_attIndex).numValues()
self.m_index = self.m_complexityIndex
self.handleEnumeratedAttribute(instances)
print("att build after numSubsets:", self.numSubsets())
else:
self.m_complexityIndex = 2
self.m_index = 0
instances.sort(instances.attribute(self.m_attIndex))
self.handleNumericAttribute(instances)
print("num build after numSubsets:", self.numSubsets())
def handleEnumeratedAttribute(self, instances: Instances):
self.m_distribution = Distribution(self.m_complexityIndex,
instances.numClasses())
for inst in instances:
if not inst.isMissing(self.m_attIndex):
self.m_distribution.add(int(inst.value(self.m_attIndex)), inst)
if self.m_distribution.check(self.m_minNoObj):
self.m_numSubsets = self.m_complexityIndex
self.m_infoGain = self.infoGainCrit.splitCritValue(
self.m_distribution, self.m_sumOfWeights)
self.m_gainRatio = self.gainRatioCrit.splitCritValue(
self.m_distribution, self.m_sumOfWeights, self.m_infoGain)
def handleNumericAttribute(self, trainInstances: Instances):
next = 1
last = 0
splitIndex = -1
self.m_distribution = Distribution(2, trainInstances.numClasses())
i = 0
for inst in trainInstances:
if inst.isMissing(self.m_attIndex):
break
self.m_distribution.add(1, inst)
i += 1
firstMiss = i
minSplit = 0.1 * self.m_distribution.total(
) / trainInstances.numClasses()
if Utils.gr(self.m_minNoObj, minSplit) or Utils.equal(
minSplit, self.m_minNoObj):
minSplit = self.m_minNoObj
elif Utils.gr(minSplit, 25):
minSplit = 25
if Utils.gr(2 * minSplit, firstMiss):
return
defaultEnt = self.infoGainCrit.oldEnt(self.m_distribution)
print("dfalut", defaultEnt)
while next < firstMiss:
if trainInstances.instance(next - 1).value(
self.m_attIndex) + 1e-5 < trainInstances.instance(
next).value(self.m_attIndex):
self.m_distribution.shiftRange(1, 0, trainInstances, last,
next)
if (Utils.gr(self.m_distribution.perBag(0), minSplit) or Utils.equal(self.m_distribution.perBag(0), minSplit))\
and (Utils.gr(self.m_distribution.perBag(1), minSplit) or Utils.equal(self.m_distribution.perBag(1), minSplit)):
currentInfoGain = self.infoGainCrit.splitCritValue(
self.m_distribution, self.m_sumOfWeights, defaultEnt)
if Utils.gr(currentInfoGain, self.m_infoGain):
self.m_infoGain = currentInfoGain
splitIndex = next - 1
self.m_index += 1
last = next
next += 1
if self.m_index == 0:
return
if self.m_useMDLcorrection:
self.m_infoGain = self.m_infoGain - (Utils.log2(self.m_index) /
self.m_sumOfWeights)
if Utils.gr(0, self.m_infoGain) or Utils.equal(0, self.m_infoGain):
return
self.m_numSubsets = 2
self.m_splitPoint = (
trainInstances.instance(splitIndex + 1).value(self.m_attIndex) +
trainInstances.instance(splitIndex).value(self.m_attIndex)) / 2
if self.m_splitPoint == trainInstances.instance(splitIndex + 1).value(
self.m_attIndex):
self.m_splitPoint = trainInstances.instance(splitIndex).value(
self.m_attIndex)
self.m_distribution = Distribution(2, trainInstances.numClasses())
self.m_distribution.addRange(0, trainInstances, 0, splitIndex + 1)
self.m_distribution.addRange(1, trainInstances, splitIndex + 1,
firstMiss)
self.m_gainRatio = self.gainRatioCrit.splitCritValue(
self.m_distribution, self.m_sumOfWeights, self.m_infoGain)
def whichSubset(self, instance: Instance):
if instance.isMissing(self.m_attIndex):
return -1
if instance.attribute(self.m_attIndex).isNominal():
return int(instance.value(self.m_attIndex))
elif instance.value(self.m_attIndex) <= self.m_splitPoint:
return 0
return 1
def rightSide(self, index: int, data: Instances):
text = ""
if data.attribute(self.m_attIndex).isNominal():
text += " = " + data.attribute(self.m_attIndex).value(index)
elif index == 0:
text += " <= " + Utils.doubleToString(self.m_splitPoint, 6)
else:
text += " > " + Utils.doubleToString(self.m_splitPoint, 6)
return text
def leftSide(self, data: Instances):
return data.attribute(self.m_attIndex).name()
def attIndex(self):
return self.m_attIndex
def splitPoint(self):
return self.m_splitPoint
def infoGain(self):
return self.m_infoGain
def gainRatio(self):
return self.m_gainRatio
def weights(self, instance: Instance):
if instance.isMissing(self.m_attIndex):
weights = []
for i in range(self.m_numSubsets):
weights.append(
self.m_distribution.perBag(i) /
self.m_distribution.total())
return weights
return None
def setSplitPoint(self, allInstances: Instances):
newSplitPoint = float("-inf")
if allInstances.attribute(
self.m_attIndex).isNumeric() and self.m_numSubsets > 1:
for i in range(allInstances.numInstances()):
instance = allInstances.instance(i)
tempValue = instance.value(self.m_attIndex)
if not Utils.isMissingValue(tempValue):
if tempValue > newSplitPoint and tempValue <= self.m_splitPoint:
newSplitPoint = tempValue
self.m_splitPoint = newSplitPoint
def resetDistribution(self, data: Instances):
insts = Instances(data, data.numInstances())
for i in range(data.numInstances()):
if self.whichSubset(data.instance(i)) > -1:
insts.add(data.instance(i))
newD = Distribution(insts, self)
newD.addInstWithUnknown(data, self.m_attIndex)
self.m_distribution = newD
def oldEnt(self,bags:Distribution):
res=0
for j in range(bags.numClasses()):
res=res+self.lnFunc(bags.perClass(j))
return (self.lnFunc(bags.total())-res)/math.log(2)
def splitEnt(self,bags:Distribution):
res=0
for i in range(bags.numBags()):
res=res+self.lnFunc(bags.perBag(i))
return (self.lnFunc(bags.total())-res)/math.log(2)
def getEstimatedErrorsForDistribution(self, theDistribution: Distribution):
if Utils.equal(theDistribution.total(), 0):
return 0
return theDistribution.numIncorrect() + Utils.addErrs(
theDistribution.total(), theDistribution.numIncorrect(), self.m_CF)