Python3 Matplotlib画简单散点图

import numpy
import matplotlib.pyplot as plt
#初始化numpy.array数组
x = numpy.array([[0, 0], [-1, 0.1], [0.3, -0.05], [0.7, 0.3], [-0.2, -0.6], [-0.15, -0.63], [-0.25, 0.55], [-0.28, 0.67]])
y = numpy.array([0, 0, 0, 0, 1, 1, 2, 2])
#Python3使用scatter画散点图，定义一个小函数
def plot_data(features, labels):
    x0,x1,x2 = features[labels==0], features[labels==1], features[labels==2]
    plt.scatter(x0[:,0], x0[:,1], c='red', s=40)   
    plt.scatter(x1[:,0], x1[:,1], c='green', s=40)
    plt.scatter(x2[:,0], x2[:,1], c= 'blue', s=40)

    plt.axis([-1.5,1.5, -1.5,1.5])#设置横纵坐标


plt.figure(1)#画第一张图
plt.subplot(221)#一块画布分为2行2列共4份，此时占用第一份
plt.title("scatter points",fontsize=24)#设置title x y
plt.xlabel("Features",fontsize=14)
plt.ylabel("Labels",fontsize=14)
plot_data(x,y)#调用函数
plt.show()#show

plt.figure(2)
plt.title("scatter points",fontsize=24)
plt.xlabel("Features",fontsize=14)
plt.ylabel("Labels",fontsize=14)
x0, x1, x2 = x[y == 0], x[y == 1], x[y == 2]
plt.scatter(x0[:, 0], x0[:, 1], marker='*', c='red', label=0, s=40)#marker定义形状，label与plt.legend画出右上角图例
plt.scatter(x1[:, 0], x1[:, 1], marker='+', c='green', label=1, s=40)# * + o  x  s是方块 d是菱形 
plt.scatter(x2[:, 0], x2[:, 1], marker='o', c='blue', label=2, s=40)
plt.axis([-1.5, 1.5, -1.5, 1.5])
plt.legend(loc='upper right')#center left lower right right upper center lower center center right lower left best.....
plt.show()

Figure1

Figure2