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不写python的日子每天都觉得没啥意思，重新搞起~ matplotlib中图的注释 直接上代码看例子： import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
#[0,5]区间，间隔0.01
t = np.arange(0.0, 5.0, 0.01)
s = np.cos(2*np.pi*t)
#lw线条宽度2
ax.plot(t, s, lw=2)
"""
'local max'为注释的文本
箭头指向坐标系中的点(2, 1)
注释文本位于坐标系点(3, 1.5)
箭头样式arrowprops=dict(facecolor='black', shrink=0.05)
"""
ax.annotate('local max', xy=(2, 1), xytext=(3, 1.5),
arrowprops=dict(facecolor='black', shrink=0.05))
#y坐标轴（-2，2）范围
ax.set_ylim(-2,2)
#作图
plt.show()
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
t = np.arange(0.0, 5.0, 0.01)
s = np.cos(2*np.pi*t)
ax.plot(t, s, lw=2)
"""
此处xycoords='data',xytext=(0.8, 0.95), textcoords='axesfraction'
是定义的注释文本的位置方式。
(0.8, 0.95)表示，注释文本位于坐标系的横坐标的80%，纵坐标的95%位置
"""
ax.annotate('local max', xy=(3, 1), xycoords='data',
xytext=(0.8, 0.95), textcoords='axes fraction',
arrowprops=dict(facecolor='black', shrink=0.05),
horizontalalignment='right', verticalalignment='top'
)
ax.set_ylim(-2,2)
plt.show()
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111, polar=True)
r = np.arange(0,1,0.001)
theta = 2*2*np.pi*r
ax.plot(theta, r, color='#ee8d18', lw=3)
ind = 800
thisr, thistheta = r[ind], theta[ind]
ax.plot([thistheta], [thisr], 'o')
ax.annotate('a polar annotation',
xy=(thistheta, thisr),
xytext=(0.05, 0.05),
#注释文本位于，相对于figure而言
textcoords='figure fraction',
arrowprops=dict(facecolor='black', shrink=0.05),
#水平对齐方式：左对齐
horizontalalignment='left',
#垂直对齐方式：bottom对齐
verticalalignment='bottom')
plt.show()
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