CODEWITHSUNDEEP
pythonpandasdataframedatetimekeyerror
SpeedyLinguine
SpeedyLinguine

Reputation: 31

In Python, the complier throws a Key Error for the datetimeIndex function even though the key is present

so i'm trying to create a list of S&P500 returns for each year and I have a pandas dataframe with the dates and closing prices of the S&P index over the past however many years. the Dates column has the format year-month-day, and i'm trying to create a new column with only the years. Whenever I use the datetimeIndex with the parameter "Dates", which is one of the dataframe columns, it throws a key error. Any tips or suggestions?

code:

import pandas as pd
import yfinance as yf
import pandas_datareader.data as web
import datetime

df = web.DataReader('^GSPC', 'yahoo', start='1980-1-1', end='2021-1-1')
clear = ['High','Low','Volume', 'Open', 'Close']

df.drop(columns = clear, inplace = True,)
print(df)

df['year'] = pd.DatetimeIndex(df['Date']).year
print(df)

Dataframe in the compiler:

>>> %Run dff.py
              Adj Close
Date                   
1980-01-02   105.760002
1980-01-03   105.220001
1980-01-04   106.519997
1980-01-07   106.809998
1980-01-08   108.949997
...                 ...
2020-12-24  3703.060059
2020-12-28  3735.360107
2020-12-29  3727.040039
2020-12-30  3732.040039
2020-12-31  3756.070068

[10340 rows x 1 columns]

error message:

Traceback (most recent call last):
  File "C:\Users\charlie\AppData\Roaming\Python\Python37\site-packages\pandas\core\indexes\base.py", line 3080, in get_loc
    return self._engine.get_loc(casted_key)
  File "pandas\_libs\index.pyx", line 70, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\index.pyx", line 101, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\hashtable_class_helper.pxi", line 4554, in pandas._libs.hashtable.PyObjectHashTable.get_item
  File "pandas\_libs\hashtable_class_helper.pxi", line 4562, in pandas._libs.hashtable.PyObjectHashTable.get_item
KeyError: 'Date'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\charlie\Desktop\ISP\dff.py", line 12, in <module>
    df['year'] = pd.DatetimeIndex(df['Date']).year
  File "C:\Users\charlie\AppData\Roaming\Python\Python37\site-packages\pandas\core\frame.py", line 3024, in __getitem__
    indexer = self.columns.get_loc(key)
  File "C:\Users\charlie\AppData\Roaming\Python\Python37\site-packages\pandas\core\indexes\base.py", line 3082, in get_loc
    raise KeyError(key) from err
KeyError: 'Date'

If the error can't be fixed, is there any other way I can do this?

Upvotes: 1

Views: 431

Answers (1)

user17242583
user17242583

Reputation:

The Date column is the index, so you have to refer to it by df.index instead of df['Date'] or df.Date:

Try this:

df['year'] = pd.DatetimeIndex(df.index).year

Upvotes: 3

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