书上把kNN抄了一遍，跑起来爽爽的：

from numpy import *

import operator

def createDataSet():

	group = array([[1.0,1.1],[1.0,1.0],[0,0],[0,0.1]])

	labels = ['A','A','B','B']

	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.iteritems(),

	 key=operator.itemgetter(1),reverse = True)

	return sortedClassCount[0][0]