绘制年月日与体重

Question

链接到“Stackoverflow question” 我是 Python 新手，并尝试了链接中的程序，但是，我收到以下错误，我在这里遗漏了什么吗？你能指出我吗？

..................

import matplotlib.pyplot as plt
import pandas as pd

df = pd.DataFrame({
          'weight':[1, 2, 3, 4],
          'date':['2011-05-01', '2013-10-10', '2015-12-17', '2017-10-29']
          })
df['date'] = pd.to_datetime(df['date'])

df1 = df.groupby(df['date'].dt.to_period('M')).sum()

df1 = df1.resample('M').asfreq().fillna(0)

plt.figure();

df1.plot(x='date', y='weight', kind='bar')


.......................................... Traceback (most recent call last):

File "/PycharmProjects/hellopython/hello_world", line 24, in

df1.plot(x='date', y='weight', kind='bar')
File "\PycharmProjects\hellopython\venv\lib\site-

packages\pandas\plotting_core.py", line 920, in call

elif not isinstance(data[x], ABCSeries):
File "\PycharmProjects\hellopython\venv\lib\site-packages\pandas\core\frame.py", line 3024, in getitem

indexer = self.columns.get_loc(key)
File "\PycharmProjects\hellopython\venv\lib\site-

packages\pandas\core\indexes\base.py", line 3082, in get_loc

raise KeyError(key) from err
KeyError: 'date'

Answer 1

两种选择

选项 1

由于date 是索引，所以我们不需要传递 x 和 y 轴来绘图。感谢@Nk03 提出这个选项。

在现有代码下修改

df1.plot(kind='bar')

代码

import matplotlib.pyplot as plt
import pandas as pd

df = pd.DataFrame({
          'weight':[1, 2, 3, 4],
          'date':['2011-05-01', '2013-10-10', '2015-12-17', '2017-10-29']
          })
df['date'] = pd.to_datetime(df['date'])

df1 = df.groupby(df['date'].dt.to_period('M')).sum()

df1 = df1.resample('M').asfreq().fillna(0)

plt.figure();

df1.plot(kind='bar')

选项 2 - 重置索引

在现有代码中添加以下行

df1 = df1.reset_index()

完整代码

import matplotlib.pyplot as plt
import pandas as pd

df = pd.DataFrame({
          'weight':[1, 2, 3, 4],
          'date':['2011-05-01', '2013-10-10', '2015-12-17', '2017-10-29']
          })
df['date'] = pd.to_datetime(df['date'])

df1 = df.groupby(df['date'].dt.to_period('M')).sum()

df1 = df1.resample('M').asfreq().fillna(0)
df1 = df1.reset_index()

plt.figure();

df1.plot(x='date', y='weight', kind='bar')