停止matplotlib在图例中重复标签 [英] Stop matplotlib repeating labels in legend

问题描述

这是一个非常简化的示例:

Here is a very simplified example:

xvalues = [2,3,4,6]

for x in xvalues:
    plt.axvline(x,color='b',label='xvalues')

plt.legend()

图例现在将在图例中四次显示'xvalues'为蓝线. 是否有比以下方法更优雅的解决方法?

The legend will now show 'xvalues' as a blue line 4 times in the legend. Is there a more elegant way of fixing this than the following?

for i,x in enumerate(xvalues):
    if not i:
        plt.axvline(x,color='b',label='xvalues')
    else:
        plt.axvline(x,color='b')

推荐答案

plt.legend以参数

1. 属于Artist对象的轴手柄的列表
2. 为字符串的标签列表

1. A list of axis handles which are Artist objects
2. A list of labels which are strings

这些参数都是可选的，默认为plt.gca().get_legend_handles_labels(). 您可以通过在调用legend之前将重复的标签放入字典中来删除重复的标签.这是因为字典不能有重复的键.

These parameters are both optional defaulting to plt.gca().get_legend_handles_labels(). You can remove duplicate labels by putting them in a dictionary before calling legend. This is because dicts can't have duplicate keys.

例如:

from collections import OrderedDict
import matplotlib.pyplot as plt

handles, labels = plt.gca().get_legend_handles_labels()
by_label = OrderedDict(zip(labels, handles))
plt.legend(by_label.values(), by_label.keys())

对于Python版本> 3.7

从Python 3.7开始，字典默认保留输入顺序.因此，不需要OrderedDict形成收集模块.

For Python versions > 3.7

As of Python 3.7, dictionaries retain input order by default. Thus, there is no need for OrderedDict form the collections module.

import matplotlib.pyplot as plt

handles, labels = plt.gca().get_legend_handles_labels()
by_label = dict(zip(labels, handles))
plt.legend(by_label.values(), by_label.keys())

="a plt.legend

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