[人工智能]【Python】matplotlib的简单使用（一）

视频教程

案例一

import matplotlib.pyplot as plt
import numpy as np

if __name__ == '__main__':
    x = np.linspace(-1,1,50)    #(-1,1)50等分,一堆的点
    y = 2 * x + 1
    plt.plot(x,y)       #横坐标、纵坐标
    plt.show()

案例二

import matplotlib.pyplot as plt
import numpy as np

if __name__ == '__main__':
    x = np.linspace(-3,3,50)    #(-1,1)50等分,一堆的点
    y1 = 2 * x + 1
    y2 = x ** 2

    plt.figure()
    plt.plot(x,y1,color = 'red',linewidth=1.0,linestyle='--')   #红线、线宽1.0、虚线
    plt.plot(x, y2)
    plt.show()

设置坐标轴

import matplotlib.pyplot as plt
import numpy as np

if __name__ == '__main__':
    x = np.linspace(-np.pi,np.pi)
    y = np.sin(x)

    plt.figure()        #创建画板
    plt.plot(x,y)

    plt.ylim(-2,2)      #设置y轴范围

    plt.show()

设置中文标签

import matplotlib.pyplot as plt
import pylab as mpl
import numpy as np

if __name__ == '__main__':
    x = np.linspace(-np.pi,np.pi )
    y = np.tan(x)

    plt.figure()        #创建画板
    plt.plot(x,y)

    mpl.rcParams['font.sans-serif'] = ['FangSong']  # 指定默认字体
    mpl.rcParams['axes.unicode_minus'] = False  # 解决保存图像是负号'-'显示为方块的问题

    plt.title("tan函数")
    plt.xlabel("横坐标")
    plt.ylabel("纵坐标")

    plt.show()

图例

import matplotlib.pyplot as plt
import numpy as np

if __name__ == '__main__':
    plt.rcParams['font.sans-serif']=['SimHei']
    plt.rcParams['axes.unicode_minus'] = False

    x = np.linspace(-np.pi,np.pi )
    y_sin = np.sin(x)
    y_cos = np.cos(x)

    plt.figure()        #创建画板
    plt.plot(x,y_sin,label='up')
    plt.plot(x,y_cos,color='red',label='down')
    plt.legend()


    plt.title("函数")
    plt.xlabel("横坐标")
    plt.ylabel("纵坐标")



    plt.show()

plt.legend(loc=‘upper left’) 设置位置

标注

待扩展

plt.xticks()

练习

import matplotlib.pyplot as plt
import numpy as np

if __name__ == '__main__':
    plt.rcParams['font.sans-serif']=['SimHei']
    plt.rcParams['axes.unicode_minus'] = False

    x = np.random.randint(0,100,10)
    y = np.random.randint(0,100,10)

    plt.figure()
    plt.scatter(x,y,color = 'limegreen',marker='s', label='city')
    plt.legend(loc='best')

    plt.title("旅行者问题")
    plt.xlabel("横坐标")
    plt.ylabel("纵坐标")



    plt.show()