import matplotlib.pyplot as plt

 import numpy as np

 x = np.arange(-10,11,1)

 y = x*x

 plt.plot(x, y)

 plt.annotate('this is the bottom',xy=(0,5),xytext=(0,20),

              arrowprops=dict(facecolor='r',frac=0.3,headwidth=20,width=10))

 # xy=(0,5)为箭头下面的点坐标，xytext=(0,20)表示说明文字的起始位置

 # arrowprops中的facecolor表示颜色，frac表示箭头占总符号的长度比例，

 # headwidth表示箭头的宽度，width表示尾部长方形的宽度

 plt.show()

 import matplotlib.pyplot as plt

 import numpy as np

 x = np.arange(-10,11,1)

 y = x*x

 plt.plot(x,y)

 # 两组进行对比

 plt.text(-2,40,'function:y=x*x',family='serif',

          size=20,color='r',style='italic',weight='black')

 plt.text(-2,20,'function:y=x*x',family='fantasy',

          size=20,color='g',style='oblique',weight='light',

          bbox=dict(facecolor='r',alpha=0.2))

 # family表示字体，size表示文字大小，color表示字体颜色，style表示斜体

 # weight表示字体的粗细，weight也可以用数字表示

 # bbox表示为字添加方框，方框里可以有颜色，透明度alpha描述

 plt.show()

 import matplotlib.pyplot as plt

 fig = plt.figure()

 ax = fig.add_subplot(111)

 ax.set_xlim([1,7])

 ax.set_ylim([1,5])

 # 在每个字符串之前要加\,如\alpha，这才表示数学符号，

 # 其它的符号在matplotlib官网上均有详细介绍

 ax.text(2,4,r'$ \alpha_i \beta_j \pi \lambda \omega $',size=25)

 ax.text(4,4,r'$ \sin(0)=\cos(\frac{\pi}{2}) $',size=25)

 ax.text(2,2,r'$ \lim_{(x \rightarrow y)} \frac{1}{x^3} $',size=25)

 ax.text(4,2,r'$ \sqrt[4]{x}=\sqrt{y} $',size=25)

 plt.show()

 import matplotlib.pyplot as plt

 import numpy as np

 x=np.linspace(0,5*np.pi,100)

 y1=np.sin(x)

 y2=np.sin(2*x)

 # 填充的区域会有线的痕迹所以可以不画线

 # plt.plot(x,y1)

 # plt.plot(x,y2)

 # 在函数曲线与x轴所围区域填充颜色

 # plt.fill(x,y1,'b',alpha=0.3)

 # plt.fill(x,y2,'r',alpha=0.3)

 fig=plt.figure()

 ax=plt.gca()

 ax.plot(x,y1,color='r')

 ax.plot(x,y2,color='b')

 # 将颜色填充到两个函数曲线所围区域

 ax.fill_between(x,y1,y2,where=y1>=y2,facecolor='y',interpolate=True)

 ax.fill_between(x,y1,y2,where=y1<y2,facecolor='g',interpolate=True)

 # where是条件表达式，

 # 当曲线不够平滑interpolate=True自动将空白的地方填充完整

 plt.show()

 import matplotlib.pyplot as plt

 import numpy as np

 import matplotlib.patches as mpatches

 fig, ax=plt.subplots() 

 # 先确定中心坐标

 xy1=np.array([0.2,0.2])

 xy2=np.array([0.2,0.8])

 xy3=np.array([0.8,0.2])

 xy4=np.array([0.8,0.8])

 circle=mpatches.Circle(xy1,0.05)  # 画圆

 ax.add_patch(circle)

 rect=mpatches.Rectangle(xy2,0.2,0.2,0.1,color='r')  # 画矩形

 ax.add_patch(rect)

 polygon=mpatches.RegularPolygon(xy3,5,0.1,color='g')  # 画多边形

 ax.add_patch(polygon)

 ellipse=mpatches.Ellipse(xy4,0.4,0.2,color='y')  # 画椭圆

 ax.add_patch(ellipse)

 # matplotlib.patches文档

 plt.axis('equal')  # x轴与y轴比例要相等

 plt.grid()

 plt.show()

 import matplotlib.pyplot as plt

 import numpy as np

 plt.style.use('ggplot')  # 为所绘制图选择风格

 fig, axes = plt.subplots(nrows=2, ncols=2, constrained_layout=True)

 ax1,ax2,ax3,ax4=axes.ravel()

 x,y=np.random.normal(size=(2,100))

 ax1.plot(x,y,'o')

 x=np.arange(0,10)

 y=np.arange(0,10)

 ncolors=len(plt.rcParams['axes.prop_cycle'])

 # prop_cycle它会有7种颜色可以循环

 shift=np.linspace(0,10,ncolors)

 for s in shift:

     ax2.plot(x,y+s,'-')

 x=np.arange(5)

 y1,y2,y3=np.random.randint(1,25,size=(3,5))

 width=0.25

 ax3.bar(x,y1,width)

 ax3.bar(x+width,y2,width)

 ax3.bar(x+2*width,y2,width)

 colors=plt.rcParams['axes.prop_cycle']

 for i, color in enumerate(colors):

     xy=np.random.normal(size=2)

     ax4.add_patch(plt.Circle(xy,radius=0.3,color=color['color']))

 ax4.axis('equal')

 plt.show()

 import matplotlib.pyplot as plt

 import numpy as np

 # r=np.empty(5)

 r=np.empty(9)

 r.fill(5)

 # r=np.arange(1,6,1)

 pi_two=np.pi*2

 # 通过极坐标绘制正8边形

 # 通过列表推导式传入多个角

 theta=[x*pi_two/8 for x in range(9)]

 # theta=[0,np.pi/2,np.pi,3*np.pi/2,2*np.pi]

 ax=plt.subplot(111,projection='polar')

 ax.plot(theta,r,color='r',linewidth=3)

 ax.grid(True)

 plt.show()

 import matplotlib.pyplot as plt

 import numpy as np

 from matplotlib.patches import Polygon

 def func(x):

     return -(x-2)*(x-8)+40

 x=np.linspace(0,10)

 y=func(x)

 fig,ax=plt.subplots()

 plt.plot(x,y,'r',linewidth=1)

 a=2

 b=9

 ax.set_xticks([a,b])

 ax.set_yticks([])

 ax.set_xticklabels(['$a$','$b$'])

 ix=np.linspace(a,b)

 iy=func(ix)

 ixy=zip(ix,iy)

 verts=[(a,0)]+list(ixy)+[(b,0)]

 poly=Polygon(verts,facecolor='0.9',edgecolor='0.5')

 ax.add_patch(poly)

 plt.figtext(0.9,0.05,'$x$')

 plt.figtext(0.1,0.9,'$y$')

 x_math=(a+b)*0.5

 y_math=30

 plt.text(x_math,y_math,r'$\int_a^b (-(x-2)*(x-8)+40)$',

          fontsize=20,horizontalalignment='center')

 # horizontalalignment='center'，会让公式自动中心对齐

 plt.ylim(ymin=25)

 plt.show()