python fix arr.contains type (#3782)

py-polars/polars/internals/expr.py

@@ -17,6 +17,7 @@
 
 from polars import internals as pli
 from polars.datatypes import (
+    Boolean,
     DataType,
     Date,
     Datetime,
@@ -3958,7 +3959,7 @@ def contains(self, item: Union[float, str, bool, int, date, datetime]) -> "Expr"
         └───────┘
 
         """
-        return wrap_expr(self._pyexpr).map(lambda s: s.arr.contains(item))
+        return wrap_expr(self._pyexpr).map(lambda s: s.arr.contains(item), Boolean)
 
     def join(self, separator: str) -> "Expr":
         """

py-polars/src/series.rs

@@ -864,12 +864,14 @@ impl PySeries {
     }
 
     #[cfg(feature = "is_in")]
-    pub fn is_in(&self, other: &PySeries) -> PyResult<Self> {
-        let out = self
-            .series
-            .is_in(&other.series)
-            .map_err(PyPolarsErr::from)?;
-        Ok(out.into_series().into())
+    pub fn is_in(&self, py: Python, other: &PySeries) -> PyResult<Self> {
+        py.allow_threads(|| {
+            let out = self
+                .series
+                .is_in(&other.series)
+                .map_err(PyPolarsErr::from)?;
+            Ok(out.into_series().into())
+        })
     }
 
     pub fn clone(&self) -> Self {

py-polars/tests/test_exprs.py

@@ -277,3 +277,20 @@ def test_regex_in_filter() -> None:
     assert df.filter(
         pl.fold(acc=False, f=lambda acc, s: acc | s, exprs=(pl.col("^nrs|flt*$") < 3))
     ).row(0) == (1, "foo", 1.0)
+
+
+def test_arr_contains() -> None:
+    df_groups = pl.DataFrame(
+        {
+            "str_list": [
+                ["cat", "mouse", "dog"],
+                ["dog", "mouse", "cat"],
+                ["dog", "mouse", "aardvark"],
+            ],
+        }
+    )
+    assert df_groups.lazy().filter(
+        pl.col("str_list").arr.contains("cat")
+    ).collect().to_dict(False) == {
+        "str_list": [["cat", "mouse", "dog"], ["dog", "mouse", "cat"]]
+    }