Question

我有一个简单的dataframe，如下所示：

    Condition   State     Value
0       A        AM      0.775651
1       B        XP      0.700265
2       A       HML      0.688315
3       A     RMSML      0.666956
4       B      XAD       0.636014
5       C       VAP      0.542897
6       C     RMSML      0.486664
7       B      XMA       0.482742
8       D      VCD       0.469553

现在，我希望每个值都有一个 barplot ，如果Condition相同，则每个状态的颜色相同。我尝试了以下python代码：

Data_Control = pd.ExcelFile('Bar_plot_example.xlsx') 
df_Control= Data_Control.parse('Sheet2')# my dataframe
s = pd.Series(df_Control.iloc[:,2].values, index=df_Control.iloc[:,1])
colors = {'A': 'r', 'B': 'b', 'C': 'g', 'D':'k'}
s.plot(kind='barh', color=[colors[i] for i in df_Control['Condition']])
plt.legend()

但是我无法针对每种情况正确获得图例。我得到以下情节。

那么我应该如何为每种情况获得正确的图例？非常感谢您的帮助。

Answer 1

因此，我在直接从熊猫进行绘图方面还没有做很多工作，但是您必须访问手柄并使用它来构造可以传递给plt.legend的手柄和标签列表。

s.plot(kind='barh', color=[colors[i] for i in df['Condition']])
# Get the original handles.
original_handles = plt.gca().get_legend_handles_labels()[0][0]

# Hold the handles and labels that will be passed to legend in lists.
handles = []
labels = []
conditions = df['Condition'].values
# Seen conditions helps us make sure that each label is added only once.
seen_conditions = set()
# Iterate over the condition and handle together.
for condition, handle in zip(conditions, original_handles):
    # If the condition was already added to the labels, then ignore it.
    if condition in seen_conditions:
        continue
    # Add the handle and label.
    handles.append(handle)
    labels.append(condition)
    seen_conditions.add(condition)

# Call legend with the stored handles and labels.
plt.legend(handles, labels)

Answer 2

您可以直接从数据中创建图例的句柄和标签：

labels = df['Condition'].unique()
handles = [plt.Rectangle((0,0),1,1, color=colors[l]) for l in labels]
plt.legend(handles, labels, title="Conditions")

完整示例：

u = """    Condition   State     Value
0       A        AM      0.775651
1       B        XP      0.700265
2       A       HML      0.688315
3       A     RMSML      0.666956
4       B      XAD       0.636014
5       C       VAP      0.542897
6       C     RMSML      0.486664
7       B      XMA       0.482742
8       D      VCD       0.469553"""

import io
import pandas as pd
import matplotlib.pyplot as plt


df = pd.read_csv(io.StringIO(u),sep="\s+" )
s = pd.Series(df.iloc[:,2].values, index=df.iloc[:,1])
colors = {'A': 'r', 'B': 'b', 'C': 'g', 'D':'k'}
s.plot(kind='barh', color=[colors[i] for i in df['Condition']])

labels = df['Condition'].unique()
handles = [plt.Rectangle((0,0),1,1, color=colors[l]) for l in labels]
plt.legend(handles, labels, title="Conditions")

plt.show()

带有固定颜色的条形图，用于python中的相同类别

2 个答案: