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learning Decision Tree #28

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1d840b8
Update KNN
dodoishere May 14, 2025
0860e4c
Updata Decision Tree.py
dodoishere May 16, 2025
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32 changes: 22 additions & 10 deletions Decision Tree/Decision Tree.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
from math import log
import operator
import pickle
from collections import defaultdict

"""
函数说明:计算给定数据集的经验熵(香农熵)
Expand All @@ -21,7 +22,7 @@
"""
def calcShannonEnt(dataSet):
numEntires = len(dataSet) #返回数据集的行数
labelCounts = {} #保存每个标签(Label)出现次数的字典
labelCounts = defaultdict(int) #简化初始化
for featVec in dataSet: #对每组特征向量进行统计
currentLabel = featVec[-1] #提取标签(Label)信息
if currentLabel not in labelCounts.keys(): #如果标签(Label)没有放入统计次数的字典,添加进去
Expand Down Expand Up @@ -204,7 +205,7 @@ def getNumLeafs(myTree):
firstStr = next(iter(myTree)) #python3中myTree.keys()返回的是dict_keys,不在是list,所以不能使用myTree.keys()[0]的方法获取结点属性，可以使用list(myTree.keys())[0]
secondDict = myTree[firstStr] #获取下一组字典
for key in secondDict.keys():
if type(secondDict[key]).__name__=='dict': #测试该结点是否为字典，如果不是字典，代表此结点为叶子结点
if isinstance(secondDict[key],dict): #测试该结点是否为字典，如果不是字典，代表此结点为叶子结点
numLeafs += getNumLeafs(secondDict[key])
else: numLeafs +=1
return numLeafs
Expand All @@ -228,7 +229,7 @@ def getTreeDepth(myTree):
firstStr = next(iter(myTree)) #python3中myTree.keys()返回的是dict_keys,不在是list,所以不能使用myTree.keys()[0]的方法获取结点属性，可以使用list(myTree.keys())[0]
secondDict = myTree[firstStr] #获取下一个字典
for key in secondDict.keys():
if type(secondDict[key]).__name__=='dict': #测试该结点是否为字典，如果不是字典，代表此结点为叶子结点
if isinstance(secondDict[key],dict): #测试该结点是否为字典，如果不是字典，代表此结点为叶子结点
thisDepth = 1 + getTreeDepth(secondDict[key])
else: thisDepth = 1
if thisDepth > maxDepth: maxDepth = thisDepth #更新层数
Expand All @@ -252,11 +253,21 @@ def getTreeDepth(myTree):
2017-07-24
"""
def plotNode(nodeTxt, centerPt, parentPt, nodeType):
arrow_args = dict(arrowstyle="<-") #定义箭头格式
font = FontProperties(fname=r"c:\windows\fonts\simsunb.ttf", size=14) #设置中文字体
createPlot.ax1.annotate(nodeTxt, xy=parentPt, xycoords='axes fraction', #绘制结点
xytext=centerPt, textcoords='axes fraction',
va="center", ha="center", bbox=nodeType, arrowprops=arrow_args, FontProperties=font)
arrow_args = dict(arrowstyle="<-") # 定义箭头格式
font = FontProperties(fname=r"c:\windows\fonts\simsunb.ttf", size=14) # 设置中文字体

createPlot.ax1.annotate(
nodeTxt,
xy=parentPt,
xycoords='axes fraction',
xytext=centerPt,
textcoords='axes fraction',
va="center",
ha="center",
bbox=nodeType,
arrowprops=arrow_args,
fontproperties=font # 直接传递 FontProperties 对象
)

"""
函数说明:标注有向边属性值
Expand Down Expand Up @@ -361,7 +372,7 @@ def classify(inputTree, featLabels, testVec):
featIndex = featLabels.index(firstStr)
for key in secondDict.keys():
if testVec[featIndex] == key:
if type(secondDict[key]).__name__ == 'dict':
if isinstance(secondDict[key],dict):
classLabel = classify(secondDict[key], featLabels, testVec)
else: classLabel = secondDict[key]
return classLabel
Expand Down Expand Up @@ -407,9 +418,10 @@ def grabTree(filename):
if __name__ == '__main__':
dataSet, labels = createDataSet()
featLabels = []
labels_copy = labels.copy() # 创建副本
myTree = createTree(dataSet, labels, featLabels)
createPlot(myTree)
testVec = [0,1] #测试数据
testVec = [0,1,1,0] #测试数据
result = classify(myTree, featLabels, testVec)
if result == 'yes':
print('放贷')
Expand Down
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