Skip to content

feat!: Allow transposing an empty DataFrame #24380

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 1 commit into
base: main
Choose a base branch
from
+21 −5
Draft

feat!: Allow transposing an empty DataFrame #24380

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 1 addition & 5 deletions crates/polars-core/src/frame/row/transpose.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -137,11 +137,7 @@ impl DataFrame {
// wasting time transposing
polars_ensure!(names_out.iter().all(|a| a.as_str() != cn), Duplicate: "{} is already in output column names", cn)
}
polars_ensure!(
df.height() != 0 && df.width() != 0,
NoData: "unable to transpose an empty DataFrame"
);
let dtype = df.get_supertype().unwrap()?;
let dtype = df.get_supertype().unwrap_or(Ok(DataType::Null))?;
df.transpose_from_dtype(&dtype, keep_names_as.map(PlSmallStr::from_str), &names_out)
}
}
Expand Down
20 changes: 20 additions & 0 deletions py-polars/tests/unit/operations/test_transpose.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,26 @@ def test_transpose_multiple_chunks() -> None:
assert_frame_equal(df.vstack(df).transpose(), expected)


def test_transpose_empty() -> None:
assert_frame_equal(pl.DataFrame().transpose(), pl.DataFrame())
assert_frame_equal(
pl.DataFrame().transpose(include_header=True),
pl.DataFrame(schema={"column": pl.String}),
)

assert pl.DataFrame(schema={"a": pl.Int32, "b": pl.Int32}).transpose().shape == (
2,
0,
)

assert_frame_equal(
pl.DataFrame(schema={"a": pl.Int32, "b": pl.Int32}).transpose(
include_header=True
),
pl.DataFrame({"column": ["a", "b"]}),
)


def test_nested_struct_transpose_21923() -> None:
df = pl.DataFrame({"x": [{"a": {"b": 1, "c": 2}}]})
assert df.transpose().item() == df.item()
Loading