python-matplotlib

# -*- coding: utf-8 -*-
import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 10, 1000)
y = np.sin(x)
z = np.cos(x**2)

# figsize:单位为英寸 dpi:指定绘图对象的分辨率,default is 80.
# 宽度现在为8*80=640
# 但是用工具栏中的保存按钮保存下来的png图像的大小是800*400像素。

plt.figure(figsize=(8,4))
# latex inserted, use it directly.
plt.plot(x,y,label="$sin(x)$",color="red",linewidth=2)
# "b--":formated string, blue and dashed line
plt.plot(x,z,"b--",label="$cos(x^2)$")
plt.xlabel("Time(s)")
plt.ylabel("Volt")
plt.title("PyPlot First Example")
plt.ylim(-2, 2)
plt.legend()
plt.show()

# figure(i) means draw ith figure. If i exists, it will not create new figure object,
# but make it as current figure object

plt.figure(1)
plt.plot(x,y,label="$sin(x)$",color="red",linewidth=2)
plt.show()
plt.figure(2)
plt.plot(x,z,"b--",label="$cos(x^2)$")
plt.show()