KNN之手写数字识别
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代码
- '''
- Created on Sep 16, 2010
- kNN: kNearest Neighbors
- Input: inX: vector to compare to existing dataset (1xN)
- dataSet: size m data set of known vectors (NxM)
- labels: data set labels (1xM vector)
- k: number of neighbors to use for comparison (should be an odd number)
- Output: the most popular class label
- @author: pbharrin
- '''
- from numpy import *
- import operator
- from os import listdir
- 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]
- 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 file2matrix(filename):
- fr = open(filename)
- numberOfLines = len(fr.readlines()) #get the number of lines in the file
- returnMat = zeros((numberOfLines,3)) #prepare matrix to return
- classLabelVector = [] #prepare labels return
- fr = open(filename)
- index = 0
- for line in fr.readlines():
- line = line.strip()
- listFromLine = line.split('\t')
- returnMat[index,:] =listFromLine[0:3]
- classLabelVector.append(int(listFromLine[-1]))
- index += 1
- return returnMat,classLabelVector
- def autoNorm(dataSet):
- minVals = dataSet.min(0)
- maxVals = dataSet.max(0)
- ranges = maxVals - minVals
- normDataSet = zeros(shape(dataSet))
- m = dataSet.shape[0]
- normDataSet = dataSet - tile(minVals, (m,1))
- normDataSet = normDataSet/tile(ranges, (m,1)) #element wise divide
- return normDataSet, ranges, minVals
- def datingClassTest():
- hoRatio = 0.50 #hold out 10%
- datingDataMat,datingLabels = file2matrix('datingTestSet2.txt') #load data setfrom file
- normMat, ranges, minVals =autoNorm(datingDataMat)
- m = normMat.shape[0]
- numTestVecs = int(m*hoRatio)
- errorCount = 0.0
- for i in range(numTestVecs):
- classifierResult = classify0(normMat[i,:],normMat[numTestVecs:m,:],datingLabels[numTestVecs:m],3)
- print "the classifier came back with: %d,the real answer is: %d" % (classifierResult,datingLabels[i])
- if (classifierResult !=datingLabels[i]): errorCount += 1.0
- print "the total error rate is: %f" % (errorCount/float(numTestVecs))
- print errorCount
- def img2vector(filename):
- returnVect = zeros((1,1024))
- fr = open(filename)
- for i in range(32):
- lineStr = fr.readline()
- for j in range(32):
- returnVect[0,32*i+j] = int(lineStr[j])
- return returnVect
- def handwritingClassTest():
- hwLabels = []
- trainingFileList = listdir('trainingDigits') #load the training set
- m = len(trainingFileList)
- trainingMat = zeros((m,1024))
- for i in range(m):
- fileNameStr = trainingFileList[i]
- fileStr = fileNameStr.split('.')[0] #take off .txt
- classNumStr = int(fileStr.split('_')[0])
- hwLabels.append(classNumStr)
- trainingMat[i,:] =img2vector('trainingDigits/%s' %fileNameStr)
- testFileList = listdir('testDigits') #iterate through the test set
- errorCount = 0.0
- mTest = len(testFileList)
- for i in range(mTest):
- fileNameStr = testFileList[i]
- fileStr = fileNameStr.split('.')[0] #take off .txt
- classNumStr = int(fileStr.split('_')[0])
- vectorUnderTest = img2vector('testDigits/%s' %fileNameStr)
- classifierResult = classify0(vectorUnderTest,trainingMat, hwLabels, 3)
- print "the classifier came back with: %d,the real answer is: %d" % (classifierResult,classNumStr)
- # if (classifierResult != classNumStr):
- # print "the classifier came back with: %s, the real answer is: %d" %(fileNameStr, classNumStr)
- if (classifierResult !=classNumStr): errorCount += 1.0
- print "\nthe total number of errorsis: %d" % errorCount
- print "\nthe total error rate is:%f" % (errorCount/float(mTest))
- handwritingClassTest()
结果
- thetotal number of errorsis: 11
- the total error rate is:0.011628
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