Panic when building a Series of lists without an inner dtype #15523

petrosbar · 2024-04-07T09:47:07Z

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I have checked that this issue has not already been reported.
I have confirmed this bug exists on the latest version of Polars.

Reproducible example

import polars as pl

pl.Series("", [["a"], []], dtype=pl.List)
# PanicException: called `Result::unwrap()` on an `Err` value: SchemaMismatch(ErrString("invalid series dtype: expected `String`, got `null`"))

Issue description

Building a Series of lists without specifying an inner dtype, panics, when values contain an empty list. (or a list with only Nones.)

Expected behavior

pl.Series("", [["a"], []], dtype=pl.List)

# shape: (2,)
# Series: '' [list[str]]
# [
#         ["a"]
#         []
# ]

petrosbar added bug Something isn't working needs triage Awaiting prioritization by a maintainer python Related to Python Polars labels Apr 7, 2024

petrosbar linked a pull request Apr 7, 2024 that will close this issue

fix: Cast empty lists and lists of only nulls without an inner dtype #15525

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deanm0000 removed the needs triage Awaiting prioritization by a maintainer label Apr 11, 2024

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Panic when building a Series of lists without an inner dtype #15523

Panic when building a Series of lists without an inner dtype #15523

petrosbar commented Apr 7, 2024 •

edited

Panic when building a Series of lists without an inner dtype #15523

Panic when building a Series of lists without an inner dtype #15523

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petrosbar commented Apr 7, 2024 • edited

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Reproducible example

Issue description

Expected behavior

petrosbar commented Apr 7, 2024 •

edited