- # scoding=utf-8
- import pylab as pl
- points = [[int(eachpoint.split("#")[0]), int(eachpoint.split("#")[1])] for eachpoint in open("points","r")]
- # 指定三个初始质心
- currentCenter1 = [20,190]; currentCenter2 = [120,90]; currentCenter3 = [170,140]
- pl.plot([currentCenter1[0]], [currentCenter1[1]],'ok')
- pl.plot([currentCenter2[0]], [currentCenter2[1]],'ok')
- pl.plot([currentCenter3[0]], [currentCenter3[1]],'ok')
- # 记录每次迭代后每个簇的质心的更新轨迹
- center1 = [currentCenter1]; center2 = [currentCenter2]; center3 = [currentCenter3]
- # 三个簇
- group1 = []; group2 = []; group3 = []
- for runtime in range(50):
- group1 = []; group2 = []; group3 = []
- for eachpoint in points:
- # 计算每个点到三个质心的距离
- distance1 = pow(abs(eachpoint[0]-currentCenter1[0]),2) + pow(abs(eachpoint[1]-currentCenter1[1]),2)
- distance2 = pow(abs(eachpoint[0]-currentCenter2[0]),2) + pow(abs(eachpoint[1]-currentCenter2[1]),2)
- distance3 = pow(abs(eachpoint[0]-currentCenter3[0]),2) + pow(abs(eachpoint[1]-currentCenter3[1]),2)
- # 将该点指派到离它最近的质心所在的簇
- mindis = min(distance1,distance2,distance3)
- if(mindis == distance1):
- group1.append(eachpoint)
- elif(mindis == distance2):
- group2.append(eachpoint)
- else:
- group3.append(eachpoint)
- # 指派完所有的点后,更新每个簇的质心
- currentCenter1 = [sum([eachpoint[0] for eachpoint in group1])/len(group1),sum([eachpoint[1] for eachpoint in group1])/len(group1)]
- currentCenter2 = [sum([eachpoint[0] for eachpoint in group2])/len(group2),sum([eachpoint[1] for eachpoint in group2])/len(group2)]
- currentCenter3 = [sum([eachpoint[0] for eachpoint in group3])/len(group3),sum([eachpoint[1] for eachpoint in group3])/len(group3)]
- # 记录该次对质心的更新
- center1.append(currentCenter1)
- center2.append(currentCenter2)
- center3.append(currentCenter3)
- # 打印所有的点,用颜色标识该点所属的簇
- pl.plot([eachpoint[0] for eachpoint in group1], [eachpoint[1] for eachpoint in group1], 'or')
- pl.plot([eachpoint[0] for eachpoint in group2], [eachpoint[1] for eachpoint in group2], 'oy')
- pl.plot([eachpoint[0] for eachpoint in group3], [eachpoint[1] for eachpoint in group3], 'og')
- # 打印每个簇的质心的更新轨迹
- for center in [center1,center2,center3]:
- pl.plot([eachcenter[0] for eachcenter in center], [eachcenter[1] for eachcenter in center],'k')
- pl.show()
- #该片段来自于http://www.codesnippet.cn/detail/010720134385.html
来源: http://www.codesnippet.cn/detail/010720134385.html