Merge pull request #88 from ym-pett/create_expr_list

feature: created expr_list and implemented simple functions for it

Author: raisadz

narwhals_daft/expr.py

@@ -13,6 +13,7 @@
 from narwhals.compliant import CompliantExpr
 
 from narwhals_daft.expr_dt import ExprDateTimeNamesSpace
+from narwhals_daft.expr_list import ExprListNamespace
 from narwhals_daft.expr_name import ExprNameNamespace
 from narwhals_daft.expr_str import ExprStringNamespace
 from narwhals_daft.utils import evaluate_literal, extend_bool, narwhals_to_native_dtype
@@ -855,6 +856,10 @@ def str(self) -> ExprStringNamespace:
     def dt(self) -> ExprDateTimeNamesSpace:
         return ExprDateTimeNamesSpace(self)
 
+    @property
+    def list(self) -> ExprListNamespace:
+        return ExprListNamespace(self)
+
     drop_nulls = not_implemented()
     fill_nan = not_implemented()
     filter = not_implemented()
@@ -871,6 +876,5 @@ def dt(self) -> ExprDateTimeNamesSpace:
 
     # namespaces
     cat = not_implemented()  # pyright: ignore[reportAssignmentType]
-    list = not_implemented()  # pyright: ignore[reportAssignmentType]
     struct = not_implemented()  # pyright: ignore[reportAssignmentType]
     any_value = not_implemented()

narwhals_daft/expr_list.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import daft.functions as F
+from narwhals._compliant.any_namespace import ListNamespace
+from narwhals._utils import not_implemented
+
+if TYPE_CHECKING:
+    from narwhals_daft.expr import DaftExpr
+
+
+class ExprListNamespace(ListNamespace["DaftExpr"]):
+    def __init__(self, expr: DaftExpr, /) -> None:
+        self._compliant = expr
+
+    @property
+    def compliant(self) -> DaftExpr:
+        return self._compliant
+
+    def len(self) -> DaftExpr:
+        return self.compliant._with_elementwise(lambda expr: F.list_count(expr, "all"))
+
+    def min(self) -> DaftExpr:
+        return self.compliant._with_elementwise(lambda expr: F.list_min(expr))
+
+    def max(self) -> DaftExpr:
+        return self.compliant._with_elementwise(lambda expr: F.list_max(expr))
+
+    def mean(self) -> DaftExpr:
+        return self.compliant._with_elementwise(lambda expr: F.list_mean(expr))
+
+    unique = not_implemented()
+    contains = not_implemented()
+    get = not_implemented()
+    median = not_implemented()
+    sum = not_implemented()

run_tests.py

@@ -55,13 +55,9 @@
     "test_joinasof_time",
     "test_kurtosis_expr",
     "test_left_to_right_broadcasting",
-    "test_len_expr",
     "test_mapping_key_not_in_expr",
-    "test_max_expr",
-    "test_mean_expr",
     "test_median_expr",
     "test_median_expr_raises_on_str",
-    "test_min_expr",
     "test_missing_columns",
     "test_mode_expr_keep_all_lazy",
     "test_mode_expr_keep_any",