pl.list fails to broadcast leading scalar input against column
Author: 0guban0vCreated Sep 11, 2026Updated Sep 15, 2026
LabelsbugpythonacceptedP-mediumA-dtype-list/array
Checks
- 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
df = pl.DataFrame({"x": [10, 20, 30]})
print(df.select(pl.list(pl.lit(1), pl.col("x"))))Log output
polars.exceptions.ShapeError: can't broadcast Series 'x' of length 3 to length 1
This error occurred in the following expression:
dyn int: 1.as_list([col("x")])Issue description
pl.list behavior depends on argument order. Leading scalar fixes output length at one, later column cannot broadcast. Reversed inputs work df.select(pl.list(pl.col("x"), pl.lit(1)))
Expected behavior
shape: (3, 1)
┌───────────┐
│ literal │
│ --- │
│ list[i64] │
╞═══════════╡
│ [1, 10] │
│ [1, 20] │
│ [1, 30] │
└───────────┘Installed versions
--------Version info---------
Polars: 1.44.2
Index type: UInt32
Platform: macOS-26.6.2-arm64-arm-64bit-Mach-O
Python: 3.13.11 (main, Jan 19 2026, 13:46:40) [Clang 17.0.0 (clang-1700.6.3.2)]
Runtime: rt32
----Optional dependencies----
Azure CLI <not installed>
adbc_driver_manager <not installed>
altair <not installed>
azure.identity <not installed>
boto3 <not installed>
cloudpickle <not installed>
connectorx <not installed>
deltalake <not installed>
fastexcel <not installed>
fsspec <not installed>
gevent <not installed>
google.auth <not installed>
great_tables <not installed>
matplotlib <not installed>
numpy <not installed>
openpyxl <not installed>
pandas <not installed>
polars_cloud <not installed>
pyarrow <not installed>
pydantic <not installed>
pyiceberg <not installed>
sqlalchemy <not installed>
torch <not installed>
xlsx2csv <not installed>
xlsxwriter <not installed>Source: pola-rs/polars