决策树入门示例(Python)

http://www.jianshu.com/p/c8f1f516e9ea

from math import log
import operator

def calcShannonEnt(dataSet): numEntries = len(dataSet) lableCounts = {} for featVec in dataSet: currentLable = featVec[-1] if currentLable not in lableCounts.keys(): lableCounts[currentLable] = 0
 lableCounts[currentLable] += 1
 shannonEnt = 0
 for key in lableCounts: prob = float(lableCounts[key])/numEntries shannonEnt -= prob * log(prob,2) return shannonEnt
def createDataSet(): dataSet = [[1,1,0,'fight'],[1,0,1,'fight'],[1,0,1,'fight'],[1,0,1,'fight'],[0,0,1,'run'],[0,1,0,'fight'],[0,1,1,'run']] lables = ['weapon','bullet','blood'] return dataSet,lables
def printData(myData): for item in myData: print('%s' % (item))


myDat,lable = createDataSet()
printData(myDat)
print(calcShannonEnt(myDat))

文章来源: blog.csdn.net，作者：网奇，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/jacke121/article/details/78034624