python函数图像加标签_图例标签没有为python中的多个绘图添加

我想读5csv文件。我有下面的函数，它分别绘制图形，我想给每个图添加一个图例。但是，我收到这个警告，即使我的函数中添加了一个标签，图例也不会被添加到绘图中。在

UserWarning: No labelled objects found. Use label='...' kwarg on individual plots.

warnings.warn("No labelled objects found. "import pandas as pd

import matplotlib.pyplot as plt

df1 = pd.read_csv('test1.csv')

df2 = pd.read_csv('test2.csv')

df3 = pd.read_csv('test3.csv')

df4 = pd.read_csv('test4.csv')

df5 = pd.read_csv('test5.csv')

def runplot(df, title, label):

rows, cols = df.shape

fig, ax = plt.subplots()

ax.plot(df['price'].values, df['cost'].values)

ax.legend()

plt.title(title)

plt.annotate('test!',

xy=(rows, df.ix[rows-1,'cost']),

xycoords='data',

xytext=(-30,30),

textcoords='offset points',

arrowprops=dict(arrowstyle="->"))

runplot(df1, 'test1.csv', label='test1')

runplot(df2, 'test2.csv', label='test2')

runplot(df3, 'test3.csv', label='test3')

runplot(df4, 'test4.csv', label='test4')

runplot(df5, 'test5.csv', label='test5')

我们怎样才能让传说在情节中展现？在