Python中的 Matplotlib.pyplot.quiverkey()

Matplotlib是Python中的一个库，它是 NumPy 库的数值数学扩展。 Pyplot是Matplotlib模块的基于状态的接口，它提供了一个类似 MATLAB 的接口。在 Pyplot 中可以使用各种图，包括线图、等高线图、直方图、散点图、3D 图等。

matplotlib.pyplot.quiverkey()函数

matplotlib 库的 pyplot 模块中的quiverkey()函数用于向 quiver plot 添加键。

Syntax: matplotlib.pyplot.quiverkey(Q, X, Y, U, label, **kw)

Parameters: This method accept the following parameters that are described below:

Q: This parameter is the Quiver instance returned by a call to quiver.
X, Y : These parameter are the x and y coordinates of the location of the key.
U: This parameter is the length of the key.
label: This parameter is a string with the length and units of the key.
angles : This parameter is the angle of the arrows.
color : This parameter is the overrides face and edge colors from Q.
labelpos : This parameter is used to position the label above, below, to the right, to the left of the arrow.
labelsep: This parameter is the distance in inches between the arrow and the label.
labelcolor: This defaults to default Text color.
fontproperties: This parameter is the dictionary with keyword arguments accepted by the FontProperties initializer: family, style, variant, size, weight.

编程需要懂一点英语

下面的示例说明了 matplotlib.axes 中的 matplotlib.pyplot.quiverkey()函数：
示例 1：

# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
        
X = np.arange(-20, 20, 0.5)
Y = np.arange(-20, 20, 0.5)
U, V = np.meshgrid(X, Y)
  
q = plt.quiver(X, Y, U, V)
plt.quiverkey(q, X = 0.5, Y = 0.5,
              U = 500, label ='Quiver key')
  
plt.title('matplotlib.pyplot.quiverkey() Example')
   
plt.show()

输出：

示例 2：

# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
        
X, Y = np.meshgrid(np.arange(0, 2 * np.pi, .2), np.arange(0, 2 * np.pi, .2))
U = np.cos(X**2)
V = np.sin(Y**2)
C = U**2 + V**2
    
Q = plt.quiver(X, Y, U, V, C, units ='width')
plt.quiverkey(Q, 0.4, 0.9, 1, 
              r'val = $Cos(x ^ 2)^2 + Sin(x ^ 2)^2$',
              labelpos ='E',
              coordinates ='figure')
  
plt.title('matplotlib.pyplot.quiverkey() Example\n', 
          fontsize = 14, fontweight ='bold')
  
plt.show()

输出：