fix(rust, python): fix panic dynamic_groupby on empty dataframe

pola-rs · Jan 18, 2023 · 8d96dd2 · 8d96dd2
1 parent 2df617e
commit 8d96dd2
Show file tree

Hide file tree

Showing 3 changed files with 15 additions and 26 deletions.
diff --git a/polars/polars-time/src/groupby/dynamic.rs b/polars/polars-time/src/groupby/dynamic.rs
@@ -214,6 +214,10 @@ impl Wrap<&DataFrame> {
         tu: TimeUnit,
         time_type: &DataType,
     ) -> PolarsResult<(Series, Vec<Series>, GroupsProxy)> {
+        if dt.is_empty() {
+            return dt.cast(time_type).map(|s| (s, by, GroupsProxy::default()));
+        }
+
         let w = Window::new(options.every, options.period, options.offset);
         let dt = dt.datetime().unwrap();
         let tz = dt.time_zone();

diff --git a/py-polars/Cargo.lock b/py-polars/Cargo.lock
diff --git a/py-polars/tests/unit/test_rolling.py b/py-polars/tests/unit/test_rolling.py
@@ -514,3 +514,12 @@ def test_groupby_dynamic_by_monday_and_offset_5444() -> None:
         ],
         "value": [4, 10, 2, 12],
     }
+
+    # test empty
+    result_empty = (
+        df.filter(pl.col("date") == "z")
+        .groupby_dynamic("date", every="1w", offset="1d", by="label", start_by="monday")
+        .agg(pl.col("value").sum())
+    )
+    print(result_empty, result)
+    assert result_empty.schema == result.schema