"Keyerror: 'open'" error occurred when I tried to draw with mplfinance

[RabbitJian]

Hello, I'm a new hand in data processing. I made an error when trying to draw with mplfinance (I think the error is probably caused by my own ignorance, but I tried for 3 hours and couldn't solve it)hope the boss can see where my error is.

I tried to process the data. This is my data

             Open   High   Low   Close   Volume
Date
2021-07-13   5400   5401  5396    5397    11544
2021-07-13   5396   5400  5396    5397    12050
2021-07-13   5398   5399  5397    5398     7252
2021-07-13   5398   5401  5397    5398    15682
2021-07-13   5399   5401  5398    5400     7292
2021-07-13   5400   5402  5399    5399    20944
2021-07-13   5399   5400  5398    5399     4174
2021-07-13   5399   5400  5397    5398     5318
2021-07-13   5398   5399  5397    5398     3340
2021-07-13   5399   5400  5393    5393     5508
2021-07-13   5392   5394  5387    5393     6362
2021-07-13   5393   5394  5390    5394     5042
2021-07-13   5394   5395  5393    5395     3320
2021-07-13   5394   5398  5393    5395     2148
2021-07-13   5395   5395  5392    5393     3310
2021-07-13   5394   5395  5391    5391     2812
2021-07-13   5392   5392  5388    5389     3020
2021-07-13   5388   5391  5386    5391     6956
2021-07-13   5389   5391  5389    5390     1944
2021-07-13   5390   5394  5388    5393     2250
2021-07-13   5392   5393  5391    5393     2134
2021-07-13   5393   5394  5390    5390     4602

This is print(df.axes)

[DatetimeIndex(['2021-07-13', '2021-07-13', '2021-07-13', '2021-07-13',
               '2021-07-13', '2021-07-13', '2021-07-13', '2021-07-13',
               '2021-07-13', '2021-07-13', '2021-07-13', '2021-07-13',
               '2021-07-13', '2021-07-13', '2021-07-13', '2021-07-13',
               '2021-07-13', '2021-07-13', '2021-07-13', '2021-07-13',
               '2021-07-13', '2021-07-13', '2021-07-13'],
              dtype='datetime64[ns]', name='Date', freq=None), Index([' Open', ' High', ' Low', ' Close', ' Volume'], dtype='object')]

This is the result of my attempt to draw

Traceback (most recent call last):
  File "D:\Program\IDE\Anaconda\lib\site-packages\pandas\core\indexes\base.py", line 3361, in get_loc
    return self._engine.get_loc(casted_key)
  File "pandas\_libs\index.pyx", line 76, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\index.pyx", line 108, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\hashtable_class_helper.pxi", line 5198, in pandas._libs.hashtable.PyObjectHashTable.get_item
  File "pandas\_libs\hashtable_class_helper.pxi", line 5206, in pandas._libs.hashtable.PyObjectHashTable.get_item
KeyError: 'Open'

  File "d:\File\workspace\VS_workspace\Python_workspace\project_K\main.py", line 28, in <module>
    mpf.plot(df)
  File "D:\Program\IDE\Anaconda\lib\site-packages\mplfinance\plotting.py", line 301, in plot
    dates,opens,highs,lows,closes,volumes = _check_and_prepare_data(data, config)
  File "D:\Program\IDE\Anaconda\lib\site-packages\mplfinance\_arg_validators.py", line 63, in _check_and_prepare_data    
    opens   = data[o].values
  File "D:\Program\IDE\Anaconda\lib\site-packages\pandas\core\frame.py", line 3458, in __getitem__
    indexer = self.columns.get_loc(key)  File "D:\Program\IDE\Anaconda\lib\site-packages\pandas\core\indexes\base.py", line 3363, in get_loc
    raise KeyError(key) from err
KeyError: 'Open'

[RabbitJian]

Sorry, friends, I've studied it carefully and found a problem. The column name of my CSV file is incorrect. My name is "open", with a space in front of it... I'm sorry to disturb you

[DanielGoldfarb]

@RabbitJian no worries. that's not uncommon. i've had the same thing happen to me at least three times in the past year. now i am in the habit that any time I see a "key error" then I closely and carefully examining my column names for possible leading or trailing blanks. I am glad you found the problem.

[881997]

Sorry, friends, I've studied it carefully and found a problem. The column name of my CSV file is incorrect. My name is "open", with a space in front of it... I'm sorry to disturb you

I write ' open' too

[DanielGoldfarb]

Since this is not entirely uncommon, and since it can be easy to not notice when there is leading or trailing whitespace in column names, I'm going to turn this Issue into an Enhancement to have the code check for leading or trailing whitespace in column names if and when a column is not found, and suggest to the user that may be the problem.