Fix sum() axis functionality

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    changed:
+    - Handle dataframe sum axis properly.

microdf/microdataframe.py

@@ -37,24 +37,42 @@ def override_df_functions(self) -> None:
                 setattr(self, name, self._create_agnostic_function(name))
 
     def _create_scalar_function(self, name: str) -> Callable:
-        """Create a scalar function that returns a Series of results.
+        def fn(*args, **kwargs) -> Union[pd.Series, float]:
+            axis = kwargs.get("axis", 0)
+            # Remove axis from kwargs since MicroSeries doesn't use it
+            ms_kwargs = {k: v for k, v in kwargs.items() if k != "axis"}
 
-        :param name: Name of the function to create
-        :return: Function that applies the operation to all columns
-        """
+            if axis == 0 or axis == "index":
+                # Column-wise: use MicroSeries methods
+                results = {}
+                for col in self.columns:
+                    if pd.api.types.is_numeric_dtype(self[col]):
+                        try:
+                            results[col] = getattr(self[col], name)(
+                                *args, **ms_kwargs
+                            )
+                        except Exception:
+                            pass
+                return pd.Series(results)
 
-        def fn(*args, **kwargs) -> pd.Series:
-            results = {}
-            for col in self.columns:
-                if pd.api.types.is_numeric_dtype(self[col]):
-                    try:
-                        results[col] = getattr(self[col], name)(
-                            *args, **kwargs
-                        )
-                    except Exception:
-                        # Skip columns that can't be aggregated
-                        pass
-            return pd.Series(results)
+            elif axis == 1 or axis == "columns":
+                # Row-wise: use pandas DataFrame methods
+                numeric_cols = [
+                    col
+                    for col in self.columns
+                    if pd.api.types.is_numeric_dtype(self[col])
+                ]
+                if numeric_cols:
+                    # Create regular DataFrame and call its method
+                    df = pd.DataFrame(
+                        {col: self[col].values for col in numeric_cols},
+                        index=self.index,
+                    )
+                    return getattr(df, name)(axis=1, *args, **ms_kwargs)
+                return pd.Series(dtype="float64", index=self.index)
+
+            else:
+                raise ValueError(f"Invalid axis: {axis}")
 
         return fn
 

microdf/tests/test_microseries_dataframe.py

@@ -287,3 +287,64 @@ def test_reset_index_inplace() -> None:
     assert "second" in mdf_multi.columns
     assert list(mdf_multi.index) == [0, 1, 2, 3]
     np.testing.assert_array_equal(mdf_multi.weights.values, weights)
+
+
+def test_sum_axis_1() -> None:
+    # Test basic row-wise sum
+    df = mdf.MicroDataFrame(
+        {"A": [1, 2, 3], "B": [4, 5, 6], "C": [7, 8, 9]},
+        weights=[0.5, 1.0, 2.0],
+    )
+
+    # Row-wise sum (axis=1) should not use weights
+    row_sums = df.sum(axis=1)
+    expected = pd.Series([12, 15, 18], index=df.index)  # 1+4+7, 2+5+8, 3+6+9
+    pd.testing.assert_series_equal(row_sums, expected)
+
+    # Column-wise sum (axis=0) should use weights
+    col_sums = df.sum(axis=0)
+    expected_weighted = pd.Series(
+        {
+            "A": 1 * 0.5 + 2 * 1.0 + 3 * 2.0,  # 8.5
+            "B": 4 * 0.5 + 5 * 1.0 + 6 * 2.0,  # 19.0
+            "C": 7 * 0.5 + 8 * 1.0 + 9 * 2.0,  # 29.5
+        }
+    )
+    pd.testing.assert_series_equal(col_sums, expected_weighted)
+
+    # Test with mixed types (non-numeric columns should be ignored)
+    df_mixed = mdf.MicroDataFrame(
+        {"A": [1, 2, 3], "B": [4, 5, 6], "text": ["a", "b", "c"]},
+        weights=[1, 1, 1],
+    )
+
+    row_sums_mixed = df_mixed.sum(axis=1)
+    expected_mixed = pd.Series([5, 7, 9], index=df_mixed.index)  # Only A+B
+    pd.testing.assert_series_equal(row_sums_mixed, expected_mixed)
+
+    # Test with axis='columns' (string form)
+    row_sums_str = df.sum(axis="columns")
+    pd.testing.assert_series_equal(row_sums_str, expected)
+
+    # Test with additional parameters
+    df_with_nan = mdf.MicroDataFrame(
+        {"A": [1, np.nan, 3], "B": [4, 5, 6], "C": [7, 8, np.nan]},
+        weights=[1, 1, 1],
+    )
+
+    # skipna=True (default)
+    row_sums_skipna = df_with_nan.sum(axis=1)
+    expected_skipna = pd.Series([12.0, 13.0, 9.0])  # NaN values skipped
+    pd.testing.assert_series_equal(row_sums_skipna, expected_skipna)
+
+    # skipna=False
+    row_sums_no_skipna = df_with_nan.sum(axis=1, skipna=False)
+    expected_no_skipna = pd.Series([12.0, np.nan, np.nan])  # NaN propagates
+    pd.testing.assert_series_equal(row_sums_no_skipna, expected_no_skipna)
+
+    # Test min_count parameter
+    row_sums_min_count = df_with_nan.sum(axis=1, min_count=3)
+    expected_min_count = pd.Series(
+        [12.0, np.nan, np.nan]
+    )  # Row 1 and 2 have < 3 non-NA values
+    pd.testing.assert_series_equal(row_sums_min_count, expected_min_count)