Python中的 Matplotlib.axes.Axes.legend()

Matplotlib是Python中的一个库，它是 NumPy 库的数值数学扩展。 Axes 类包含大部分图形元素：Axis、Tick、Line2D、Text、Polygon 等，并设置坐标系。 Axes 的实例通过回调属性支持回调。

matplotlib.axes.Axes.legend()函数

matplotlib 库的 axes 模块中的Axes.legend()函数用于在轴上放置图例。

Syntax: Axes.legend(self, *args, **kwargs)

Parameters: This method accepts the following parameters.

• labels : This parameter is the list of labels to show next to the artists.
• handles : This parameter is the list of Artists (lines, patches) to be added to the legend.

Returns:This method returns the matplotlib.legend.Legend instance.

下面的示例说明了 matplotlib.axes 中的 matplotlib.axes.Axes.legend()函数：

示例 1：

# Implementation of matplotlib function
import matplotlib.pyplot as plt
  
fig, ax = plt.subplots()
  
line1, = ax.plot([1, 2, 3],
                 label ="Line 1",
                 color ="black", 
                 linewidth = 4,
                 linestyle =':')
  
line2, = ax.plot([3, 2, 1], 
                 label ="Line 2",
                 color ="green", 
                 linewidth = 4)
  
  
first_legend = ax.legend(handles =[line1], 
                         loc ='upper center')
  
ax.add_artist(first_legend)
  
ax.legend(handles =[line2], loc ='lower center')
  
fig.suptitle('matplotlib.axes.Axes.legend() \
function Example\n', fontweight ="bold")
  
plt.show()

输出：

示例 2：

# Implementation of matplotlib function
import numpy as np
import matplotlib.pyplot as plt
  
np.random.seed(19680801)
  
fig, ax = plt.subplots()
for color in [ 'tab:green', 'tab:blue',
               'tab:orange']:
    n = 70
    x, y = np.random.rand(2, n)
    scale = 1000.0 * np.random.rand(n)
    ax.scatter(x, y, c = color, s = scale,
               label = color,
               alpha = 0.35)
  
ax.legend()
ax.grid(True)
fig.suptitle('matplotlib.axes.Axes.legend() function\
 Example\n', fontweight ="bold")
  
plt.show()

输出：