Merge pull request #92 from raisadz/feat/fill_nan_pow

feat: add `fill_nan` and fix `pow`

Author: MarcoGorelli

narwhals_daft/expr.py

@@ -420,11 +420,9 @@ def __rmod__(self, other: DaftExpr) -> DaftExpr:
         )
 
     def __pow__(self, other: DaftExpr) -> DaftExpr:
-        if other._metadata.is_literal:
-            other_lit = evaluate_literal(other)
-            return self._with_callable(lambda expr: (expr**other_lit))
-        msg = "`pow` with non-literal input is not yet supported"
-        raise NotImplementedError(msg)
+        return self._with_elementwise(
+            lambda _input, expr: F.pow(_input, expr), expr=other
+        )
 
     def __rpow__(self, other: DaftExpr) -> DaftExpr:
         if other._metadata.is_literal:
@@ -844,6 +842,14 @@ def _partitioned_rank(
 
         return self._with_callable(_unpartitioned_rank, _partitioned_rank)
 
+    def fill_nan(self, value: float | None) -> DaftExpr:
+        def func(expr: Expression) -> Expression:
+            if value is None:
+                return F.when(expr.is_nan(), lit(None)).otherwise(expr)
+            return expr.fill_nan(lit(value))
+
+        return self._with_callable(func)
+
     @property
     def name(self) -> ExprNameNamespace:
         return ExprNameNamespace(self)
@@ -861,7 +867,6 @@ def list(self) -> ExprListNamespace:
         return ExprListNamespace(self)
 
     drop_nulls = not_implemented()
-    fill_nan = not_implemented()
     filter = not_implemented()
     ewm_mean = not_implemented()
     kurtosis = not_implemented()

run_tests.py

@@ -7,7 +7,6 @@
     "test_any_value_expr",
     "test_any_value_group_by",
     "test_any_value_over",
-    "test_arithmetic_expr",
     "test_arithmetic_expr_left_literal",
     "test_cast",
     "test_cast_binary",
@@ -33,7 +32,6 @@
     "test_expr_binary",
     "test_expr_floordiv_by_zero",
     "test_expr_rfloordiv_by_zero",
-    "test_fill_nan",
     "test_fill_null_limits",
     "test_fill_null_strategies_with_limit_as_none",
     "test_fill_null_strategies_with_partition_by",
@@ -81,7 +79,6 @@
     "test_over_when_then_aggregation_partition_by",
     "test_package_version",
     "test_parse_weight",
-    "test_pipe_expr",
     "test_quantile_expr",
     "test_rank_with_order_by",
     "test_rank_with_order_by_and_partition_by",