[BUG-REPORT] empty filtered dataframe cannot be sliced

[Ben-Epstein]

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Description Please provide a clear and concise description of the problem. This should contain all the steps needed to reproduce the problem. A minimal code example that exposes the problem is very appreciated.

Software information

• Vaex version (import vaex; vaex.__version__): 4.10
• Vaex was installed via: pip / conda-forge / from source pip
• OS: mac/linux

Additional information

import vaex

df = vaex.example()
df_empty = df[df.x==4]
df_empty[:3]  # RuntimeError: end index should be larger or equal to start index

[JovanVeljanoski]

What would you expect to get? Since the dataframe you are slicing is empty..

[Ben-Epstein]

@JovanVeljanoski I'd expect an empty dataframe.

At least a helpful error if not, but I think it's reasonable to get an empty df

See below

x=[1,2,3]
y=x[:0]

z = y[:2]
print(x,y,z)

[maartenbreddels]

Yes, good point! Do you want to open a PR with a test in tests/slice_test.py? Then I'm happy to fix it! Do you agree @JovanVeljanoski ?

[JovanVeljanoski]

Agreed. Unit-test made