Draw a scatter plot with python

import numpy as np
import pylab as pl

pl.rcParams['font.sans-serif']=['SimHei']#解决标题、坐标轴标签不能是中文的问题
pl.rcParams['axes.unicode_minus']=False#标题等默认是英文输出
a=np.arange(-4*np.pi,4*np.pi,0.1)
b=np.cos(a)
pl.scatter(a,b)#绘制散点图
pl.title('余弦散点图')
pl.show()