diff --git a/crates/polars-ops/src/series/ops/cut.rs b/crates/polars-ops/src/series/ops/cut.rs index 2deb6dfeb52f..cba643cf98e9 100644 --- a/crates/polars-ops/src/series/ops/cut.rs +++ b/crates/polars-ops/src/series/ops/cut.rs @@ -131,15 +131,19 @@ pub fn qcut( ) -> PolarsResult { polars_ensure!(!probs.iter().any(|x| x.is_nan()), ComputeError: "quantiles cannot be NaN"); + if s.null_count() == s.len() { + // If we only have nulls we don't have any breakpoints. + return Ok(Series::full_null( + s.name().clone(), + s.len(), + &DataType::Categorical(None, Default::default()), + )); + } + let s = s.cast(&DataType::Float64)?; let s2 = s.sort(SortOptions::default())?; let ca = s2.f64()?; - if ca.null_count() == ca.len() { - // If we only have nulls we don't have any breakpoints. - return cut(&s, vec![], labels, left_closed, include_breaks); - } - let f = |&p| { ca.quantile(p, QuantileInterpolOptions::Linear) .unwrap() diff --git a/py-polars/tests/unit/operations/test_qcut.py b/py-polars/tests/unit/operations/test_qcut.py index e92afba49dda..7b7b1c399a45 100644 --- a/py-polars/tests/unit/operations/test_qcut.py +++ b/py-polars/tests/unit/operations/test_qcut.py @@ -100,6 +100,15 @@ def test_qcut_full_null() -> None: assert_series_equal(result, expected, categorical_as_str=True) +def test_qcut_full_null_with_labels() -> None: + s = pl.Series("a", [None, None, None, None]) + + result = s.qcut([0.25, 0.50], labels=["1", "2", "3"]) + + expected = pl.Series("a", [None, None, None, None], dtype=pl.Categorical) + assert_series_equal(result, expected, categorical_as_str=True) + + def test_qcut_allow_duplicates() -> None: s = pl.Series([1, 2, 2, 3])