diff --git a/src/python/10.kmeans/kMeans.py b/src/python/10.kmeans/kMeans.py new file mode 100644 index 00000000..b485ce14 --- /dev/null +++ b/src/python/10.kmeans/kMeans.py @@ -0,0 +1,50 @@ +#!/usr/bin/python +# coding:utf8 + +from numpy import * + +# 从文本中构建矩阵,加载文本文件,然后处理 +def loadDataSet(fileName): # 通用函数,用来解析以 tab 键分隔的 floats(浮点数) + dataMat = [] # assume last column is target value + fr = open(fileName) + for line in fr.readlines(): + curLine = line.strip().split('\t') + fltLine = map(float,curLine) # 映射所有的元素为 float(浮点数)类型 + dataMat.append(fltLine) + return dataMat + +# 计算两个向量的欧式距离(可根据场景选择) +def distEclud(vecA, vecB): + return sqrt(sum(power(vecA - vecB, 2))) # la.norm(vecA-vecB) + +# 为给定数据集构建一个包含 k 个随机质心的集合。随机质心必须要在整个数据集的边界之内,这可以通过找到数据集每一维的最小和最大值来完成。然后生成 0~1.0 之间的随机数并通过取值范围和最小值,以便确保随机点在数据的边界之内。 +def randCent(dataSet, k): + n = shape(dataSet)[1] # 列数 + centroids = mat(zeros((k,n))) # 创建质心矩阵 + for j in range(n): # 穿件随机簇质心,并且在每一维的边界内 + minJ = min(dataSet[:,j]) + rangeJ = float(max(dataSet[:,j]) - minJ) + centroids[:,j] = mat(minJ + rangeJ * random.rand(k,1)) # 随机生成 + return centroids + +# k-means 聚类算法 +def kMeans(dataSet, k, distMeas=distEclud, createCent=randCent): + m = shape(dataSet)[0] + clusterAssment = mat(zeros((m,2))) # 创建矩阵来分配数据点到质心中 + centroids = createCent(dataSet, k) + clusterChanged = True + while clusterChanged: + clusterChanged = False + for i in range(m): # 循环每一个数据点并分配到最近的质心中去 + minDist = inf; minIndex = -1 + for j in range(k): + distJI = distMeas(centroids[j,:],dataSet[i,:]) + if distJI < minDist: + minDist = distJI; minIndex = j + if clusterAssment[i,0] != minIndex: clusterChanged = True + clusterAssment[i,:] = minIndex,minDist**2 + print centroids + for cent in range(k): # 重新计算质心 + ptsInClust = dataSet[nonzero(clusterAssment[:,0].A==cent)[0]] # 获取该簇中的所有点 + centroids[cent,:] = mean(ptsInClust, axis=0) # 分配质心 + return centroids, clusterAssment