pyhon: rows return date and datetime

polars/polars-lazy/src/dsl.rs

@@ -149,6 +149,15 @@ impl GetOutput {
             f(&flds[0])
         }))
     }
+
+    pub fn map_dtype<F: 'static + Fn(&DataType) -> DataType + Send + Sync>(f: F) -> Self {
+        NoEq::new(Arc::new(move |_: &Schema, _: Context, flds: &[Field]| {
+            let mut fld = flds[0].clone();
+            let new_type = f(fld.data_type());
+            fld.coerce(new_type);
+            fld
+        }))
+    }
 }
 
 impl<F> FunctionOutputField for F

py-polars/docs/source/reference/expression.rst

@@ -188,6 +188,7 @@ Manipulation/ selection
     Expr.upper_bound
     Expr.str_concat
     Expr.reshape
+    Series.to_physical
 
 Column names
 ------------

py-polars/polars/internals/expr.py

@@ -191,6 +191,17 @@ def function(s: "pli.Series") -> "pli.Series":
 
         return self.map(function, return_dtype=dtype)
 
+    def to_physical(self) -> "Expr":
+        """
+        Cast to physical representation of the logical dtype.
+
+        Date -> Int32
+        Datetime -> Int64
+        Time -> Int64
+        other -> other
+        """
+        return wrap_expr(self._pyexpr.to_physical())
+
     def sqrt(self) -> "Expr":
         """
         Compute the square root of the elements

py-polars/src/conversion.rs

@@ -146,11 +146,25 @@ impl IntoPy<PyObject> for Wrap<AnyValue<'_>> {
                 let s = rev.get(idx);
                 s.into_py(py)
             }
-            AnyValue::Date(v) => v.into_py(py),
-            AnyValue::Datetime(v) => v.into_py(py),
+            AnyValue::Date(v) => {
+                let pl = PyModule::import(py, "polars").unwrap();
+                let pli = pl.getattr("internals").unwrap();
+                let m_series = pli.getattr("series").unwrap();
+                let convert = m_series.getattr("_to_python_datetime").unwrap();
+                let py_date_dtype = pl.getattr("Date").unwrap();
+                convert.call1((v, py_date_dtype)).unwrap().into_py(py)
+            }
+            AnyValue::Datetime(v) => {
+                let pl = PyModule::import(py, "polars").unwrap();
+                let pli = pl.getattr("internals").unwrap();
+                let m_series = pli.getattr("series").unwrap();
+                let convert = m_series.getattr("_to_python_datetime").unwrap();
+                let py_datetime_dtype = pl.getattr("Datetime").unwrap();
+                convert.call1((v, py_datetime_dtype)).unwrap().into_py(py)
+            }
             AnyValue::Time(v) => v.into_py(py),
             AnyValue::List(v) => {
-                let pypolars = PyModule::import(py, "polars").expect("polars installed");
+                let pypolars = PyModule::import(py, "polars").unwrap();
                 let pyseries = PySeries::new(v);
                 let python_series_wrapper = pypolars
                     .getattr("wrap_s")

py-polars/src/lazy/dsl.rs

@@ -980,6 +980,16 @@ impl PyExpr {
     pub fn cumcount(&self, reverse: bool) -> Self {
         self.inner.clone().cumcount(reverse).into()
     }
+
+    pub fn to_physical(&self) -> Self {
+        self.inner
+            .clone()
+            .map(
+                |s| Ok(s.to_physical_repr().into_owned()),
+                GetOutput::map_dtype(|dt| dt.to_physical()),
+            )
+            .into()
+    }
 }
 
 impl From<dsl::Expr> for PyExpr {

py-polars/tests/test_datelike.py

@@ -202,7 +202,6 @@ def test_timezone() -> None:
 
 
 def test_to_list() -> None:
-
     s = pl.Series("date", [123543, 283478, 1243]).cast(pl.Date)
 
     out = s.to_list()
@@ -211,3 +210,13 @@ def test_to_list() -> None:
     s = pl.Series("datetime", [123543, 283478, 1243]).cast(pl.Datetime)
     out = s.to_list()
     assert out[0] == datetime(1970, 1, 1, 0, 2, 3, 543000)
+
+
+def test_rows() -> None:
+    s0 = pl.Series("date", [123543, 283478, 1243]).cast(pl.Date)
+    s1 = pl.Series("datetime", [123543, 283478, 1243]).cast(pl.Datetime)
+    df = pl.DataFrame([s0, s1])
+
+    rows = df.rows()
+    assert rows[0][0] == date(2308, 4, 2)
+    assert rows[0][1] == datetime(1970, 1, 1, 0, 2, 3, 543000)