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举例：机器学习实战教程（一）：K-近邻算法（史诗级干货长文）

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from matplotlib.font_manager import FontProperties import matplotlib.lines as mlines import matplotlib.pyplot as plt import numpy as np   def file2matrix(fileName):     fr = open(fileName)     arrayOfLines = fr.readlines()     numberOfLines = len(arrayOfLines)     returnMat = np.zeros((numberOfLines, 3))     classLabelVector = []     index = 0           for line in arrayOfLines:         line = line.strip()         listFromLine = line.split('\t')         # 不包括3，所以就是前三个         returnMat[index, :] = listFromLine[0:3]         if listFromLine[-1] == 'didntLike':             classLabelVector.append(1)         elif listFromLine[-1] == 'smallDoses':             classLabelVector.append(2)         elif listFromLine[-1] == 'largeDoses':             classLabelVector.append(3)         index += 1     return returnMat, classLabelVector   def showData(datingDatMat, datingLabels):           fig, axs = plt.subplots(nrows=2, ncols=2, sharex=False, sharey=False, figsize=(13, 8))           numberOfLabels = len(datingLabels)     LabelsColors = []           for i in datingLabels:         if i == 1:             LabelsColors.append('green')         if i == 2:             LabelsColors.append('blue')         if i == 3:             LabelsColors.append('red')           # fig 1     # 颜色是一个 list，对应每一组数据有一个颜色对应     axs[0][0].scatter(x=datingDatMat[:,0], y=datingDatMat[:,1], color=LabelsColors, s=15, alpha=0.5)           axs0_title_text = axs[0][0].set_title('Fight Hours & Video Game Percentage')     axs0_xlabel_text = axs[0][0].set_xlabel('Flight Hours')     axs0_ylabel_text = axs[0][0].set_ylabel('Video Game Percentage')           plt.setp(axs0_title_text, size=14, color='red')     plt.setp(axs0_xlabel_text, size=10, color='brown')     plt.setp(axs0_ylabel_text, size=10, color= 'brown')           # fig 2     axs[0][1].scatter(x=datingDatMat[:,0], y=datingDatMat[:,2], color=LabelsColors, s=15, alpha=0.5)           axs1_title_text = axs[0][1].set_title('Fight Hours & Ice Cream Weight')     axs1_xlabel_text = axs[0][1].set_xlabel('Flight Hours')     axs1_ylabel_text = axs[0][1].set_ylabel('Ice Cream Weight')           plt.setp(axs1_title_text, size=14,  color='red')     plt.setp(axs1_xlabel_text, size=10, color='brown')     plt.setp(axs1_ylabel_text, size=10, color= 'brown')           # fig 3     axs[1][0].scatter(x=datingDatMat[:,1], y=datingDatMat[:,2], color=LabelsColors, s=15, alpha=0.5)           axs2_title_text = axs[1][0].set_title('Video Game Percentage & Ice Cream Weight')     axs2_xlabel_text = axs[1][0].set_xlabel('Video Game Percentage')     axs2_ylabel_text = axs[1][0].set_ylabel('Ice Cream Weight')           plt.setp(axs2_title_text, size=14,  color='red')     plt.setp(axs2_xlabel_text, size=10, color='brown')     plt.setp(axs2_ylabel_text, size=10, color= 'brown')           # legend     didntlike = mlines.Line2D([], [], color='green', marker='.', markersize=6, label='didntLike')     smallDoses = mlines.Line2D([], [], color='blue', marker='.', markersize=6, label='smallDoses')     largeDoses = mlines.Line2D([], [], color='red', marker='.', markersize=6, label='largeDoses')           # Add legend     axs[0][0].legend(handles=[didntlike, smallDoses, largeDoses])     axs[0][1].legend(handles=[didntlike, smallDoses, largeDoses])     axs[1][0].legend(handles=[didntlike, smallDoses, largeDoses])       plt.tight_layout()     plt.show()       if __name__ == '__main__':     fileName = 'datingTestSet.txt'     datingDataMat, datingLabels = file2matrix(fileName)     showData(datingDataMat, datingLabels)