Finds and ID3 Algorithm

"""
 -*- coding: utf-8 -*-
 Created on 2019/10/21 21:02
 FINDS
 @Author  : Zhouy
 @Blog    : www.crocodilezs.top

"""

# create dataset
def CreateDataset():
    dataset = [['Sunny', 'Warm', 'Normal', 'Strong', 'Warm', 'Same', 'Yes'],
               ['Sunny', 'Warm', 'High', 'Strong', 'Warm', 'Same', 'Yes'],
               ['Rainy', 'Cold', 'High', 'Strong', 'Warm', 'Change', 'No'],
               ['Sunny', 'Warm', 'High', 'Strong', 'Cold', 'Change', 'Yes']]
    labels = ['Sky', 'Temp', 'Humidity', 'Wind', 'Water', 'Forest', 'OutdoorSport']
    return dataset, labels

# Find one version space by using FINDS
# '/' means null, and '*' means generalization
def FINDS(dataset):
    constraint = ['/', '/', '/', '/', '/', '/']
    for item in dataset:
        if item[-1] == 'Yes':
            # only go through positive instances
            for i in range(len(item)-1):
                if(item[i] != constraint[i] and constraint[i] != '*'):
                    if(constraint[i] == '/'):
                        constraint[i] = item[i]
                    else:
                        constraint[i] = '*'
    return constraint

def main():
    dataset, labels = CreateDataset()
    constraint = FINDS(dataset)
    print(constraint)

if __name__ == "__main__":
    main()

"""
 -*- coding: utf-8 -*-
 Created on 2019/10/22 11:59
 myTrees
 @Author  : Zhouy
 @Blog    : www.crocodilezs.top

"""
from math import log
import operator


# 原始数据
def createDataSet():
    dataSet = [[1, 1, 'yes'],
               [1, 1, 'yes'],
               [1, 0, 'no'],
               [0, 1, 'no'],
               [0, 1, 'no']]
    labels = ['no surfacing','flippers']
    return dataSet, labels

# 多数表决器
# 列中相同值数量最多为结果
def majorityCnt(classList):
    classCounts = {}
    for value in classList:
        if (value not in classCounts.keys()):
            classCounts[value] = 0
        classCounts[value] += 1
    sortedClassCount = sorted(classCounts.iteritems(), key=operator.itemgetter(1), reverse=True)
    return sortedClassCount[0][0]


# 划分数据集
# dataSet:原始数据集
# axis:进行分割的指定列索引
# value:指定列中的值
def splitDataSet(dataSet, axis, value):
    retDataSet = []
    for featDataVal in dataSet:
        if featDataVal[axis] == value:
            # 下面两行去除某一项指定列的值，很巧妙有没有
            reducedFeatVal = featDataVal[:axis]
            reducedFeatVal.extend(featDataVal[axis + 1:])
            retDataSet.append(reducedFeatVal)
    return retDataSet


# 计算香农熵
def calcShannonEnt(dataSet):
    # 数据集总项数
    numEntries = len(dataSet)
    # 标签计数对象初始化
    labelCounts = {}
    for featDataVal in dataSet:
        # 获取数据集每一项的最后一列的标签值
        currentLabel = featDataVal[-1]
        # 如果当前标签不在标签存储对象里，则初始化，然后计数
        if currentLabel not in labelCounts.keys():
            labelCounts[currentLabel] = 0
        labelCounts[currentLabel] += 1
    # 熵初始化
    shannonEnt = 0.0
    # 遍历标签对象，求概率，计算熵
    for key in labelCounts.keys():
        prop = labelCounts[key] / float(numEntries)
        shannonEnt -= prop * log(prop, 2)
    return shannonEnt


# 选出最优特征列索引
def chooseBestFeatureToSplit(dataSet):
    # 计算特征个数，dataSet最后一列是标签属性，不是特征量
    numFeatures = len(dataSet[0]) - 1
    # 计算初始数据香农熵
    baseEntropy = calcShannonEnt(dataSet)
    # 初始化信息增益，最优划分特征列索引
    bestInfoGain = 0.0
    bestFeatureIndex = -1
    for i in range(numFeatures):
        # 获取每一列数据
        featList = [example[i] for example in dataSet]
        # 将每一列数据去重
        uniqueVals = set(featList)
        newEntropy = 0.0
        for value in uniqueVals:
            subDataSet = splitDataSet(dataSet, i, value)
            # 计算条件概率
            prob = len(subDataSet) / float(len(dataSet))
            # 计算条件熵
            newEntropy += prob * calcShannonEnt(subDataSet)
        # 计算信息增益
        infoGain = baseEntropy - newEntropy
        if (infoGain > bestInfoGain):
            bestInfoGain = infoGain
            bestFeatureIndex = i
    return bestFeatureIndex


# 决策树创建
def createTree(dataSet, labels):
    # 获取标签属性，dataSet最后一列，区别于labels标签名称
    classList = [example[-1] for example in dataSet]
    # 树极端终止条件判断
    # 标签属性值全部相同，返回标签属性第一项值
    if classList.count(classList[0]) == len(classList):
        return classList[0]
    # 只有一个特征（1列）
    if len(dataSet[0]) == 1:
        return majorityCnt(classList)
    # 获取最优特征列索引
    bestFeatureIndex = chooseBestFeatureToSplit(dataSet)
    # 获取最优索引对应的标签名称
    bestFeatureLabel = labels[bestFeatureIndex]
    # 创建根节点
    myTree = {bestFeatureLabel: {}}
    # 去除最优索引对应的标签名，使labels标签能正确遍历
    del (labels[bestFeatureIndex])
    # 获取最优列
    bestFeature = [example[bestFeatureIndex] for example in dataSet]
    uniquesVals = set(bestFeature)
    for value in uniquesVals:
        # 子标签名称集合
        subLabels = labels[:]
        # 递归
        myTree[bestFeatureLabel][value] = createTree(splitDataSet(dataSet, bestFeatureIndex, value), subLabels)
    return myTree


# 获取分类结果
# inputTree:决策树字典
# featLabels:标签列表
# testVec:测试向量  例如：简单实例下某一路径 [1,1]  => yes（树干值组合，从根结点到叶子节点）
def classify(inputTree, featLabels, testVec):
    # 获取根结点名称，将dict转化为list
    firstSide = list(inputTree.keys())
    # 根结点名称String类型
    firstStr = firstSide[0]
    # 获取根结点对应的子节点
    secondDict = inputTree[firstStr]
    # 获取根结点名称在标签列表中对应的索引
    featIndex = featLabels.index(firstStr)
    # 由索引获取向量表中的对应值
    key = testVec[featIndex]
    # 获取树干向量后的对象
    valueOfFeat = secondDict[key]
    # 判断是子结点还是叶子节点：子结点就回调分类函数，叶子结点就是分类结果
    # if type(valueOfFeat).__name__=='dict': 等价 if isinstance(valueOfFeat, dict):
    if isinstance(valueOfFeat, dict):
        classLabel = classify(valueOfFeat, featLabels, testVec)
    else:
        classLabel = valueOfFeat
    return classLabel


# 将决策树分类器存储在磁盘中，filename一般保存为txt格式
def storeTree(inputTree, filename):
    import pickle
    fw = open(filename, 'wb+')
    pickle.dump(inputTree, fw)
    fw.close()


# 将瓷盘中的对象加载出来，这里的filename就是上面函数中的txt文件
def grabTree(filename):
    import pickle
    fr = open(filename, 'rb')
    return pickle.load(fr)

"""
 -*- coding: utf-8 -*-
 Created on 2019/10/22 12:00
 treePlotter
 @Author  : Zhouy
 @Blog    : www.crocodilezs.top

"""
import matplotlib.pyplot as plt

decisionNode = dict(boxstyle="sawtooth", fc="0.8")
leafNode = dict(boxstyle="round4", fc="0.8")
arrow_args = dict(arrowstyle="<-")


# 获取树的叶子节点
def getNumLeafs(myTree):
    numLeafs = 0
    # dict转化为list
    firstSides = list(myTree.keys())
    firstStr = firstSides[0]
    secondDict = myTree[firstStr]
    for key in secondDict.keys():
        # 判断是否是叶子节点（通过类型判断，子类不存在，则类型为str；子类存在，则为dict）
        if type(secondDict[
                    key]).__name__ == 'dict':  # test to see if the nodes are dictonaires, if not they are leaf nodes
            numLeafs += getNumLeafs(secondDict[key])
        else:
            numLeafs += 1
    return numLeafs


# 获取树的层数
def getTreeDepth(myTree):
    maxDepth = 0
    # dict转化为list
    firstSides = list(myTree.keys())
    firstStr = firstSides[0]
    secondDict = myTree[firstStr]
    for key in secondDict.keys():
        if type(secondDict[
                    key]).__name__ == 'dict':  # test to see if the nodes are dictonaires, if not they are leaf nodes
            thisDepth = 1 + getTreeDepth(secondDict[key])
        else:
            thisDepth = 1
        if thisDepth > maxDepth: maxDepth = thisDepth
    return maxDepth


def plotNode(nodeTxt, centerPt, parentPt, nodeType):
    createPlot.ax1.annotate(nodeTxt, xy=parentPt, xycoords='axes fraction',
                            xytext=centerPt, textcoords='axes fraction',
                            va="center", ha="center", bbox=nodeType, arrowprops=arrow_args)


def plotMidText(cntrPt, parentPt, txtString):
    xMid = (parentPt[0] - cntrPt[0]) / 2.0 + cntrPt[0]
    yMid = (parentPt[1] - cntrPt[1]) / 2.0 + cntrPt[1]
    createPlot.ax1.text(xMid, yMid, txtString, va="center", ha="center", rotation=30)


def plotTree(myTree, parentPt, nodeTxt):  # if the first key tells you what feat was split on
    numLeafs = getNumLeafs(myTree)  # this determines the x width of this tree
    depth = getTreeDepth(myTree)
    firstSides = list(myTree.keys())
    firstStr = firstSides[0]  # the text label for this node should be this
    cntrPt = (plotTree.xOff + (1.0 + float(numLeafs)) / 2.0 / plotTree.totalW, plotTree.yOff)
    plotMidText(cntrPt, parentPt, nodeTxt)
    plotNode(firstStr, cntrPt, parentPt, decisionNode)
    secondDict = myTree[firstStr]
    plotTree.yOff = plotTree.yOff - 1.0 / plotTree.totalD
    for key in secondDict.keys():
        if type(secondDict[
                    key]).__name__ == 'dict':  # test to see if the nodes are dictonaires, if not they are leaf nodes
            plotTree(secondDict[key], cntrPt, str(key))  # recursion
        else:  # it's a leaf node print the leaf node
            plotTree.xOff = plotTree.xOff + 1.0 / plotTree.totalW
            plotNode(secondDict[key], (plotTree.xOff, plotTree.yOff), cntrPt, leafNode)
            plotMidText((plotTree.xOff, plotTree.yOff), cntrPt, str(key))
    plotTree.yOff = plotTree.yOff + 1.0 / plotTree.totalD


# if you do get a dictonary you know it's a tree, and the first element will be another dict
# 绘制决策树
def createPlot(inTree):
    fig = plt.figure(1, facecolor='white')
    fig.clf()
    axprops = dict(xticks=[], yticks=[])
    createPlot.ax1 = plt.subplot(111, frameon=False, **axprops)  # no ticks
    # createPlot.ax1 = plt.subplot(111, frameon=False) #ticks for demo puropses
    plotTree.totalW = float(getNumLeafs(inTree))
    plotTree.totalD = float(getTreeDepth(inTree))
    plotTree.xOff = -0.5 / plotTree.totalW
    plotTree.yOff = 1.0
    plotTree(inTree, (0.5, 1.0), '')
    plt.show()


# 绘制树的根节点和叶子节点（根节点形状：长方形，叶子节点：椭圆形）
# def createPlot():
#    fig = plt.figure(1, facecolor='white')
#    fig.clf()
#    createPlot.ax1 = plt.subplot(111, frameon=False) #ticks for demo puropses
#    plotNode('a decision node', (0.5, 0.1), (0.1, 0.5), decisionNode)
#    plotNode('a leaf node', (0.8, 0.1), (0.3, 0.8), leafNode)
#    plt.show()

def retrieveTree(i):
    listOfTrees = [{'no surfacing': {0: 'no', 1: {'flippers': {0: 'no', 1: 'yes'}}}},
                   {'no surfacing': {0: 'no', 1: {'flippers': {0: {'head': {0: 'no', 1: 'yes'}}, 1: 'no'}}}}
                   ]
    return listOfTrees[i]


# thisTree = retrieveTree(0)
# createPlot(thisTree)
# createPlot()
# myTree = retrieveTree(0)
# numLeafs =getNumLeafs(myTree)
# treeDepth =getTreeDepth(myTree)
# print(u"叶子节点数目：%d"% numLeafs)
# print(u"树深度：%d"%treeDepth)

"""
 -*- coding: utf-8 -*-
 Created on 2019/10/22 12:00
 testTrees_3
 @Author  : Zhouy
 @Blog    : www.crocodilezs.top

"""
import myTrees as mt
import treePlotter as tp
#测试
dataSet, labels = mt.createDataSet()
#copy函数：新开辟一块内存，然后将list的所有值复制到新开辟的内存中
labels1 = labels.copy()
#createTree函数中将labels1的值改变了，所以在分类测试时不能用labels1
myTree = mt.createTree(dataSet,labels1)
#保存树到本地
mt.storeTree(myTree,'myTree.txt')
#在本地磁盘获取树
myTree = mt.grabTree('myTree.txt')
print (u"决策树结构：%s"%myTree)
#绘制决策树
print(u"绘制决策树：")
tp.createPlot(myTree)
numLeafs =tp.getNumLeafs(myTree)
treeDepth =tp.getTreeDepth(myTree)
print(u"叶子节点数目：%d"% numLeafs)
print(u"树深度：%d"%treeDepth)
#测试分类 简单样本数据3列
labelResult =mt.classify(myTree,labels,[1,1])
print(u"[1,1] 测试结果为：%s"%labelResult)
labelResult =mt.classify(myTree,labels,[1,0])
print(u"[1,0] 测试结果为：%s"%labelResult)