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Index error - columns vs non-column - Printable Version

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Index error - columns vs non-column - Vinny - Aug-03-2021

Dear users,

I am getting an IndexError, and not sure why? The code (below) works perfectly when I run it using data.cvs. On that type of file, the index is a column (named Date).

But, if I run the code directly from an input library (e.i., df = yf.download(tickers=ticker, start=start, end=end), I receive the trackback message's below. In this example, the date is not considered a column. So, I think the error comes from that; however, I don't know how to fix it.

I hope I am being clear. It is my first post, and I am a beginner.

Thank you

This is my Code:
df_close_adj = pd.DataFrame(data=df[["Close", "Adj_Close"]].to_numpy(), index=df["Date"], columns=[["Close", "Adj_Close"]])
The Traceback I get is this:

Error:
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
/usr/local/lib/python3.7/dist-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   2897             try:
-> 2898                 return self._engine.get_loc(casted_key)
   2899             except KeyError as err:

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item()

KeyError: 'Date'

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

KeyError                                  Traceback (most recent call last)
2 frames
/usr/local/lib/python3.7/dist-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   2898                 return self._engine.get_loc(casted_key)
   2899             except KeyError as err:
-> 2900                 raise KeyError(key) from err
   2901 
   2902         if tolerance is not None:

KeyError: 'Date'


RE: Index error - columns vs non-column - jamesaarr - Aug-05-2021

Hello,

I've not used Pandas too much but I believe the error is where you are referencing the index. Index, in case you didn't already know is how the code refers to items on a list or table, for example

0. Apple, 1. Pear, 2. Peach

So item 0 is always the first item on the list. Try changing "Date" to the index value of that column.

I don't know if that is the solution, however nobody else replied so I thought I would give it a go.

Kind regards,
James

RE: Index error - columns vs non-column - Vinny - Aug-09-2021

Hi James,

Thanks for stopping by. I really appreciate your time and effort in trying to help me. Unfortunately, it did not work, BUT I will persuade on my studies, and I hope to figure it out sooner or later.

I am a Python beginner.

Thank you, and have a great week!

Yours sincerely,

Vinny

(Aug-05-2021, 10:45 AM)jamesaarr Wrote: Hello,

I've not used Pandas too much but I believe the error is where you are referencing the index. Index, in case you didn't already know is how the code refers to items on a list or table, for example

0. Apple, 1. Pear, 2. Peach

So item 0 is always the first item on the list. Try changing "Date" to the index value of that column.

I don't know if that is the solution, however nobody else replied so I thought I would give it a go.

Kind regards,
James


RE: Index error - columns vs non-column - snippsat - Aug-09-2021

The error is clear and the problem lay in df Dataframe.
When do index=df["Date"] means that the Dataframe most have column named Date.
To show a example.
import pandas as pd

data = {
    "Name": ["Tom", "nick", "krish", "jack"],
    "Date": [20, 21, 19, 18],
}

df = pd.DataFrame(data)
>>> df
    Name  Date
0    Tom    20
1   nick    21
2  krish    19
3   jack    18

>>> df['Date']
0    20
1    21
2    19
3    18
Name: Date, dtype: int64

>>> df.columns
Index(['Name', 'Date'], dtype='object')
If eg put a space in Date string it will fail with your error.
>>> df['Date']
Traceback (most recent call last):
.....  
KeyError: 'Date'

# Date most be the exact name and a column in df
>>> df.columns
Index(['Name', 'Date '], dtype='object')