python 实现简单的KNN算法

Posted 2021-01-02 byerHu

from numpy import *
import operator

def createDataSet():
    group = array([[3,104],[2,100],[1,81],[101,10],[99,5],[98,2]])
    labels = [‘爱情片‘,‘爱情片‘,‘爱情片‘,‘动作片‘,‘动作片‘,‘动作片‘]
    return group, labels

def classify0(inX, dataSet, labels, k):
    dataSetSize = dataSet.shape[0]
    diffMat = tile(inX, (dataSetSize,1)) - dataSet
    sqDiffMat = diffMat ** 2
    sqDistances = sqDiffMat.sum(axis=1)
    distances = sqDistances ** 0.5
    sortedDistIndicies = distances.argsort()
    classCount = {}
    for i in range(k):
        voteIlabel = labels[sortedDistIndicies[i]]
        classCount[voteIlabel] = classCount.get(voteIlabel,0) + 1
    sortedClassCount = sorted(classCount.items(),key=operator.itemgetter(1),reverse=True)
    return sortedClassCount[0][0]

group,labels = createDataSet()
print(classify0([500,90],group,labels,3))