两列子图，子标题和总图标题
from IPython.display import set_matplotlib_formats
from matplotlib import pyplot as plt
# 生成数据做出散点图
set_matplotlib_formats('retina') # 打印高清图
plt.rcParams['figure.figsize'] = (20,10) # rc: run configuration
plt.subplot(121)
plt.scatter(x=features[:, 0].asnumpy(), y=labels.asnumpy(), s=1) # s: scale 设置点的大小
plt.title('k=2')
plt.subplot(122)
plt.scatter(x=features[:, 1].asnumpy(), y=labels.asnumpy(), s=1) # s: scale 设置点的大小
plt.title('k=-3.4')
plt.suptitle('two features') # 子图的总图标题
plt.show()
