refactor: make approximate ops subclasses of their non-approximate va…

…riants

ibis/backends/clickhouse/tests/test_aggregations.py

@@ -62,7 +62,7 @@ def test_reduction_invalid_where(alltypes, reduction):
         ),
         (
             lambda t, cond: t.int_col.approx_median(),
-            lambda df, cond: np.int32(df.int_col.median()),
+            lambda df, cond: df.int_col.median(),
         ),
         (
             lambda t, cond: t.double_col.min(),

ibis/expr/operations/reductions.py

@@ -210,6 +210,11 @@ class Median(QuantileBase):
     """Compute the median of a column."""
 
 
+@public
+class ApproxMedian(Median):
+    """Compute the approximate median of a column."""
+
+
 @public
 class Quantile(QuantileBase):
     """Compute the quantile of a column."""
@@ -325,25 +330,6 @@ class ArgMin(Filterable, Reduction):
     dtype = rlz.dtype_like("arg")
 
 
-@public
-class ApproxCountDistinct(Filterable, Reduction):
-    """Approximate number of unique values."""
-
-    arg: Column
-
-    # Impala 2.0 and higher returns a DOUBLE
-    dtype = dt.int64
-
-
-@public
-class ApproxMedian(Filterable, Reduction):
-    """Compute the approximate median of a set of comparable values."""
-
-    arg: Column
-
-    dtype = rlz.dtype_like("arg")
-
-
 @public
 class GroupConcat(Filterable, Reduction):
     """Concatenate strings in a group with a given separator character."""
@@ -364,6 +350,11 @@ class CountDistinct(Filterable, Reduction):
     dtype = dt.int64
 
 
+@public
+class ApproxCountDistinct(CountDistinct):
+    """Approximate number of unique values."""
+
+
 @public
 class ArrayCollect(Filterable, Reduction):
     """Collect values into an array."""

ibis/expr/types/generic.py

@@ -1644,13 +1644,13 @@ def approx_median(self, where: ir.BooleanValue | None = None) -> Scalar:
         >>> ibis.options.interactive = True
         >>> t = ibis.examples.penguins.fetch()
         >>> t.body_mass_g.approx_median()
-        ┌──────┐
-        │ 4030 │
-        └──────┘
+        ┌────────┐
+        │ 4030.0 │
+        └────────┘
         >>> t.body_mass_g.approx_median(where=t.species == "Chinstrap")
-        ┌──────┐
-        │ 3700 │
-        └──────┘
+        ┌────────┐
+        │ 3700.0 │
+        └────────┘
         """
         return ops.ApproxMedian(self, where=self._bind_to_parent_table(where)).to_expr()