QST: Indexing over empty DataFrame

[YarShev]

• I have searched the [pandas] tag on StackOverflow for similar questions.

• I have asked my usage related question on StackOverflow.

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Question about pandas

Is it correct behavior when indexing over empty DataFrame?

import pandas
df = pandas.DataFrame()
df
Empty DataFrame
Columns: []
Index: []

df.iloc[:, 3:9] # this doesn't throw an exception
Empty DataFrame
Columns: []
Index: []

df.iloc[:, 3] # this throws the exception
IndexError: single positional indexer is out-of-bounds

df[3:9] # this doesn't throw an exception
Empty DataFrame
Columns: []
Index: []

df[3] # this throws the exception
KeyError: 3

[attack68]

You will find that this is not just an empty DataFrame:

s = pd.Series([1,2])
s.loc[10:20] -> Series([], dtype: int64)
s.iloc[10:20] -> Series([], dtype: int64)

An automated set of indexing constructions can be seen here: #39775

Also a discussion here: #39424

[asishm-wk]

It's similar for python lists / numpy arrays as well

>>> b = []
>>> b[3]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: list index out of range
>>> b[3:5]
[]
>>> a = np.array([])
>>> a[3]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: index 3 is out of bounds for axis 0 with size 0
>>> a[3:5]
array([], dtype=float64)

[YarShev]

@attack68 , @asishm-wk , thanks! That makes sense.

[mroeschke]

Closing since the expected behavior has been explained.