matplotlib条形图从类别数据框列添加图例 [英] matplotlib bar plot add legend from categories dataframe column

问题描述

我尝试添加图例，根据我的示例，该图例应输出:

1. 带有水果一词和
的红色正方形
2. 带有单词的绿色方块素食.

我尝试了几种方法(下面的示例只是许多试验中的一种)，但是我无法使其正常工作.

有人可以告诉我如何解决这个问题吗?

 将pandas导入为pd从matplotlib导入pyplot作为plt数据= [['apple'，'fruit'，10]，['nanaba'，'fruit'，15]，['salat'，'veggie'，144]]数据= pd.DataFrame(数据，列= ['对象'，'类型'，'值'])颜色= {'水果':'红色'，'蔬菜':'绿色'}c = data ['Type'].apply(lambda x:colors [x])条= plt.bar(数据['对象']，数据['值']，颜色= c，标签=颜色)plt.legend() 

解决方案

为不在轴上的对象创建图例的通常方法是创建代理艺术家，如

I try to add the legend which should, according to my example, output:

1. a red square with the word fruit and
2. a green square with the word veggie.

I tried several things (the example below is just 1 of the many trials), but I can't get it work.

Can someone tell me how to solve this problem?

import pandas as pd
from matplotlib import pyplot as plt
data = [['apple', 'fruit', 10], ['nanaba', 'fruit', 15], ['salat','veggie', 144]] 
data = pd.DataFrame(data, columns = ['Object', 'Type', 'Value']) 

colors = {'fruit':'red', 'veggie':'green'}           
c = data['Type'].apply(lambda x: colors[x])

bars = plt.bar(data['Object'], data['Value'], color=c, label=colors)
plt.legend()

解决方案

The usual way to create a legend for objects which are not in the axes would be to create proxy artists as shown in the legend guide

Here,

colors = {'fruit':'red', 'veggie':'green'}         
labels = list(colors.keys())
handles = [plt.Rectangle((0,0),1,1, color=colors[label]) for label in labels]
plt.legend(handles, labels)

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