BUG: rolling.count with axis=1

doc/source/whatsnew/v0.25.0.rst

@@ -387,6 +387,7 @@ Groupby/Resample/Rolling
 - Ensured that ordering of outputs in ``groupby`` aggregation functions is consistent across all versions of Python (:issue:`25692`)
 - Ensured that result group order is correct when grouping on an ordered ``Categorical`` and specifying ``observed=True`` (:issue:`25871`, :issue:`25167`)
 - Bug in :meth:`pandas.core.window.Rolling.min` and :meth:`pandas.core.window.Rolling.max` that caused a memory leak (:issue:`25893`)
+- Bug in :meth:`pandas.core.window.Rolling.count` and `pandas.core.window.Expanding.count` was previously ignoring the axis keyword (:issue:`13503`)
 - Bug in :meth:`pandas.core.groupby.GroupBy.idxmax` and :meth:`pandas.core.groupby.GroupBy.idxmin` with datetime column would return incorrect dtype (:issue:`25444`, :issue:`15306`)
 - Bug in :meth:`pandas.core.groupby.GroupBy.cumsum`, :meth:`pandas.core.groupby.GroupBy.cumprod`, :meth:`pandas.core.groupby.GroupBy.cummin` and :meth:`pandas.core.groupby.GroupBy.cummax` with categorical column having absent categories, would return incorrect result or segfault (:issue:`16771`)
 

pandas/core/window.py

@@ -938,6 +938,7 @@ def count(self):
             result = b.notna().astype(int)
             result = self._constructor(result, window=window, min_periods=0,
                                        center=self.center,
+                                       axis=self.axis,
                                        closed=self.closed).sum()
             results.append(result)
 

pandas/tests/test_window.py

@@ -648,7 +648,7 @@ def test_iter_raises(self, klass):
         with pytest.raises(NotImplementedError):
             iter(obj.rolling(2))
 
-    def test_rolling_axis(self, axis_frame):
+    def test_rolling_axis_sum(self, axis_frame):
         # see gh-23372.
         df = DataFrame(np.ones((10, 20)))
         axis = df._get_axis_number(axis_frame)
@@ -667,6 +667,20 @@ def test_rolling_axis(self, axis_frame):
         result = df.rolling(3, axis=axis_frame).sum()
         tm.assert_frame_equal(result, expected)
 
+    def test_rolling_axis_count(self, axis_frame):
+        # see gh-26055
+        df = DataFrame({'x': range(3), 'y': range(3)})
+
+        axis = df._get_axis_number(axis_frame)
+
+        if axis in [0, 'index']:
+            expected = DataFrame({'x': [1.0, 2.0, 2.0], 'y': [1.0, 2.0, 2.0]})
+        else:
+            expected = DataFrame({'x': [1.0, 1.0, 1.0], 'y': [2.0, 2.0, 2.0]})
+
+        result = df.rolling(2, axis=axis_frame).count()
+        tm.assert_frame_equal(result, expected)
+
 
 class TestExpanding(Base):