Python 具有多个图例条目的 Matplotlib 直方图
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Matplotlib histogram with multiple legend entries
提问by warrenfitzhenry
I have this code that produces a histogram, identifying three types of fields; "Low", "medium" , and "high":
我有这段代码可以生成直方图，识别三种类型的字段；“低”、“中”和“高”：
import pylab as plt
import pandas as pd
df = pd.read_csv('April2017NEW.csv', index_col =1)
df1 = df.loc['Output Energy, (Wh/h)'] # choose index value and Average
df1['Average'] = df1.mean(axis=1)
N, bins, patches = plt.hist(df1['Average'], 30)
cmap = plt.get_cmap('jet')
low = cmap(0.5)
medium =cmap(0.25)
high = cmap(0.8)
for i in range(0,4):
patches[i].set_facecolor(low)
for i in range(4,11):
patches[i].set_facecolor(medium)
for i in range(11,30):
patches[i].set_facecolor(high)
plt.xlabel("Watt Hours", fontsize=16)
plt.ylabel("Households", fontsize=16)
plt.xticks(fontsize=14)
plt.yticks(fontsize=14)
ax = plt.subplot(111)
ax.spines["top"].set_visible(False)
ax.spines["right"].set_visible(False)
plt.show()
that produces this:
产生这个：
How do I get a legend in there for the three different colors?
我如何获得三种不同颜色的图例？
回答by ImportanceOfBeingErnest
You would need to create the legend yourself. To this end, create some rectangles, which are not shown in the figure (so called proxy artists).
您需要自己创建图例。为此，创建一些图中未显示的矩形（所谓的代理艺术家）。
#create legend
handles = [Rectangle((0,0),1,1,color=c,ec="k") for c in [low,medium, high]]
labels= ["low","medium", "high"]
plt.legend(handles, labels)
Complete example:
完整示例：
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.patches import Rectangle
data = np.random.rayleigh(size=1000)*35
N, bins, patches = plt.hist(data, 30, ec="k")
cmap = plt.get_cmap('jet')
low = cmap(0.5)
medium =cmap(0.25)
high = cmap(0.8)
for i in range(0,4):
patches[i].set_facecolor(low)
for i in range(4,11):
patches[i].set_facecolor(medium)
for i in range(11,30):
patches[i].set_facecolor(high)
#create legend
handles = [Rectangle((0,0),1,1,color=c,ec="k") for c in [low,medium, high]]
labels= ["low","medium", "high"]
plt.legend(handles, labels)
plt.xlabel("Watt Hours", fontsize=16)
plt.ylabel("Households", fontsize=16)
plt.xticks(fontsize=14)
plt.yticks(fontsize=14)
plt.gca().spines["top"].set_visible(False)
plt.gca().spines["right"].set_visible(False)
plt.show()
回答by tsando
According to me you just need to pass the required label as an argument in the histfunction, e.g.
根据我的说法，您只需要将所需的标签作为函数中的参数传递hist，例如
plt.hist(x, bins=20, alpha=0.5, label='my label')
See example also here https://matplotlib.org/examples/statistics/histogram_demo_multihist.html
另请参见此处的示例https://matplotlib.org/examples/statistics/histogram_demo_multihist.html
