BUG: rolling.count with axis=1

doc/source/whatsnew/v0.25.0.rst

@@ -384,6 +384,7 @@ Groupby/Resample/Rolling
 - 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 :func:`idxmax` and :func:`idxmin` on :meth:`DataFrame.groupby` with datetime column would return incorrect dtype (:issue:`25444`, :issue:`15306`)
+- Bug in :meth:`pandas.core.window._Rolling_and_Expanding.count` that did not include axis parameter in constructor call (:issue:`13503`)
 
 Reshaping
 ^^^^^^^^^

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 +667,23 @@ 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):
+        # see gh-26055
+        df = DataFrame({'x': range(3), 'y': range(3)})
+
+        result = df.rolling(2).count()
+        expected = DataFrame({'x': [1.0, 2.0, 2.0], 'y': [1.0, 2.0, 2.0]})
+        tm.assert_frame_equal(result, expected)
+
+        # not specifiying axis and making axis=rows
+        # are expected to yield the same result
+        result = df.rolling(2, axis='rows').count()
+        tm.assert_frame_equal(result, expected)
+
+        result = df.rolling(2, axis='columns').count()
+        expected = DataFrame({'x': [1.0, 1.0, 1.0], 'y': [2.0, 2.0, 2.0]})
+        tm.assert_frame_equal(result, expected)
+
 
 class TestExpanding(Base):