带有索引的 Pandas Plot 导致“KeyError [] 不在索引中”
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Pandas Plot with Index causes 'KeyError [] not in index'
提问by lammy
I am very new to the Pandas concept in Python. Usually plots are not a problem. However, I am now confronted with a dataframe that contains an index. Somehow nothing is working anymore.
我对 Python 中的 Pandas 概念非常陌生。通常地块不是问题。但是，我现在面临一个包含索引的数据框。不知何故，没有任何工作了。
What I want to achieve: Create a subplot for every column [Plant1,Plant2,Plant3] against one specific colum [Trafo1].
我想要实现的目标：针对一个特定的列 [Trafo1]，为每一列 [Plant1,Plant2,Plant3] 创建一个子图。
Here is my code:
这是我的代码：
import numpy as np
import datetime
import numpy as np
import matplotlib
import matplotlib.pyplot as plt
import pandas as pd
import os
# Create the sample data
plant1 = {'Date' : pd.date_range('1/1/2011', periods=10, freq='D'),
'Plant' : pd.Series(["Plant1"]*10),
'Output' : pd.Series(abs(np.random.randn(10)))}
plant2 = {'Date' : pd.date_range('1/3/2011', periods=10, freq='D'),
'Plant' : pd.Series(["Plant2"]*10),
'Output' : pd.Series(abs(np.random.randn(10)))}
plant3 = {'Date' : pd.date_range('1/5/2011', periods=10, freq='D'),
'Plant' : pd.Series(["Plant3"]*10),
'Output' : pd.Series(abs(np.random.randn(10)))}
trafo1 = {'Date' : pd.date_range('1/5/2011', periods=10, freq='D'),
'Plant' : pd.Series(["Trafo1"]*10),
'Output' : pd.Series(abs(np.random.randn(10)))}
trafo2 = {'Date' : pd.date_range('1/5/2011', periods=10, freq='D'),
'Plant' : pd.Series(["Trafo2"]*10),
'Output' : pd.Series(abs(np.random.randn(10)))}
df_plant_1 = pd.DataFrame(plant1)
df_plant_2 = pd.DataFrame(plant2)
df_plant_3 = pd.DataFrame(plant3)
df_trafo_1 = pd.DataFrame(trafo1)
df_trafo_2 = pd.DataFrame(trafo2)
sample = pd.concat([df_plant_1,df_plant_2,df_plant_3,df_trafo_1,df_trafo_2])
test = pd.pivot_table(sample, index='Date', columns='Plant', values='Output')
test = test.fillna(method='pad')
test = test.fillna(method='bfill')
# Draw the plots
matplotlib.style.use('ggplot')
cols = len(test.columns) - 1
fig, axes = plt.subplots(nrows=cols/2, ncols=2, figsize=(12, 4))
for column in test.iloc[:,:-1]:
test.plot(x=test[column], y=test['Trafo1'], title=column)
plt.gca().set_aspect('equal', adjustable='box')
plt.show()
Resulting in the following error output:
导致以下错误输出：
runfile('C:/..../untitled12.py', wdir='C:/...')
?
Traceback (most recent call last):
File "<ipython-input-206-1acb55933d7f>", line 1, in <module>
runfile('C:/Users/bjl/untitled12.py', wdir='C:/Users/bjl')
File "C:\Anaconda2\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 699, in runfile
execfile(filename, namespace)
File "C:\Anaconda2\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 74, in execfile
exec(compile(scripttext, filename, 'exec'), glob, loc)
File "C:/Users/bjl/untitled12.py", line 52, in <module>
test.plot(x=test[column], y=test['Trafo1'], title=column)
File "C:\Anaconda2\lib\site-packages\pandas\tools\plotting.py", line 3671, in __call__
sort_columns=sort_columns, **kwds)
File "C:\Anaconda2\lib\site-packages\pandas\tools\plotting.py", line 2556, in plot_frame
**kwds)
File "C:\Anaconda2\lib\site-packages\pandas\tools\plotting.py", line 2370, in _plot
series = data[y].copy() # Don't modify
File "C:\Anaconda2\lib\site-packages\pandas\core\frame.py", line 1963, in __getitem__
return self._getitem_array(key)
File "C:\Anaconda2\lib\site-packages\pandas\core\frame.py", line 2007, in _getitem_array
indexer = self.ix._convert_to_indexer(key, axis=1)
File "C:\Anaconda2\lib\site-packages\pandas\core\indexing.py", line 1150, in _convert_to_indexer
raise KeyError('%s not in index' % objarr[mask])
KeyError: '[ 1.20311253 1.20311253 1.20311253 1.20311253 1.20311253 0.32765014\n 1.65686117 2.58118029 0.58903059 0.13907876 0.59270297 0.27072611\n 0.50167366 1.0310578 ] not in index'
I don't understand what the problem with the Index appears to be. I was not able to find any help online as all examples work without index.
我不明白索引的问题是什么。我无法在线找到任何帮助，因为所有示例都没有索引。
I really appreciate your help. The error is a cryptic to newcomers.
我真的很感谢你的帮助。这个错误对新手来说是个谜。
回答by PdevG
According to the docsyou are supposed to give the column names, not the columns themselves when plotting this way. So replacing:
根据文档，您应该在以这种方式绘制时给出列名称，而不是列本身。所以更换：
test.plot(x=test[column], y=test['Trafo1'], title=column)
with
和
test.plot(x=column, y='Trafo1', title=column)
should solve this error.
应该解决这个错误。
EDIT: As for the subplotting, to get it in the right subplot you have to specify the axis you want your plot to end up. You could so in the following manner:
编辑：至于子绘图，要将其放入正确的子图中，您必须指定您希望绘图结束的轴。你可以通过以下方式：
for i, column in enumerate(test.iloc[:, :-2]):
j = i // 2
k = i % 2
test.plot(x=column, y='Trafo1', title=column, ax=axes[j][k])
Now do the operation you wanted on all axes (Although it really screws stuff up)
现在在所有轴上执行您想要的操作（虽然它真的搞砸了）
for ax in axes.reshape(4):
ax.set_aspect('equal', adjustable='box')
Show plots :)
显示情节:)
plt.show()
