BUG: Switched shapes in ValueError msg in DataFrame construct (pandas-dev#20742)

Author: meiermark

doc/source/whatsnew/v0.24.0.rst

@@ -1852,6 +1852,7 @@ Other
 ^^^^^
 
 - Bug where C variables were declared with external linkage causing import errors if certain other C libraries were imported before Pandas. (:issue:`24113`)
+- Switched shape in ``ValueError`` message when constructiong a :class:`DataFrame` with parameters ``columns`` and ``index`` not matching the shape of the input data. (:issue:`20742`)
 
 .. _whatsnew_0.24.0.contributors:
 

pandas/core/internals/managers.py

@@ -1673,8 +1673,8 @@ def create_block_manager_from_arrays(arrays, names, axes):
 
 def construction_error(tot_items, block_shape, axes, e=None):
     """ raise a helpful message about our construction """
-    passed = tuple(map(int, [tot_items] + list(block_shape)))
-    implied = tuple(map(int, [len(ax) for ax in axes]))
+    passed = tuple(map(int, reversed([tot_items] + list(block_shape))))
+    implied = tuple(map(int, reversed([len(ax) for ax in axes])))
     if passed == implied and e is not None:
         raise e
     if block_shape[0] == 0:

pandas/tests/frame/test_constructors.py

@@ -386,25 +386,35 @@ def test_constructor_error_msgs(self):
                        'B': ['a', 'b', 'c']})
 
         # wrong size ndarray, GH 3105
-        msg = r"Shape of passed values is \(3, 4\), indices imply \(3, 3\)"
+        msg = r"Shape of passed values is \(4, 3\), indices imply \(3, 3\)"
         with pytest.raises(ValueError, match=msg):
             DataFrame(np.arange(12).reshape((4, 3)),
                       columns=['foo', 'bar', 'baz'],
                       index=pd.date_range('2000-01-01', periods=3))
 
+        # see issue #20742
+        msg = r"Shape of passed values is \(1, 3\), indices imply \(1, 4\)"
+        with pytest.raises(ValueError, match=msg):
+            df = pd.DataFrame(index=[0], columns=range(0, 4), data=np.array([[4,5,6]]))
+
+        # see issue #20742
+        msg = r"Shape of passed values is \(3, 1\), indices imply \(1, 4\)"
+        with pytest.raises(ValueError, match=msg):
+            df = pd.DataFrame(index=[0], columns=range(0, 4), data=np.array([4,5,6]))
+
         # higher dim raise exception
         with pytest.raises(ValueError, match='Must pass 2-d input'):
             DataFrame(np.zeros((3, 3, 3)), columns=['A', 'B', 'C'], index=[1])
 
         # wrong size axis labels
         msg = ("Shape of passed values "
-               r"is \(3, 2\), indices "
-               r"imply \(3, 1\)")
+               r"is \(2, 3\), indices "
+               r"imply \(1, 3\)")
         with pytest.raises(ValueError, match=msg):
             DataFrame(np.random.rand(2, 3), columns=['A', 'B', 'C'], index=[1])
 
         msg = ("Shape of passed values "
-               r"is \(3, 2\), indices "
+               r"is \(2, 3\), indices "
                r"imply \(2, 2\)")
         with pytest.raises(ValueError, match=msg):
             DataFrame(np.random.rand(2, 3), columns=['A', 'B'], index=[1, 2])
@@ -638,10 +648,10 @@ def _check_basic_constructor(self, empty):
         assert frame.values.dtype == np.int64
 
         # wrong size axis labels
-        msg = r'Shape of passed values is \(3, 2\), indices imply \(3, 1\)'
+        msg = r'Shape of passed values is \(2, 3\), indices imply \(1, 3\)'
         with pytest.raises(ValueError, match=msg):
             DataFrame(mat, columns=['A', 'B', 'C'], index=[1])
-        msg = r'Shape of passed values is \(3, 2\), indices imply \(2, 2\)'
+        msg = r'Shape of passed values is \(2, 3\), indices imply \(2, 2\)'
         with pytest.raises(ValueError, match=msg):
             DataFrame(mat, columns=['A', 'B'], index=[1, 2])
 
@@ -1805,7 +1815,7 @@ def test_from_records_to_records(self):
         tm.assert_frame_equal(DataFrame.from_records(arr2), DataFrame(arr2))
 
         # wrong length
-        msg = r'Shape of passed values is \(3, 2\), indices imply \(3, 1\)'
+        msg = r'Shape of passed values is \(2, 3\), indices imply \(1, 3\)'
         with pytest.raises(ValueError, match=msg):
             DataFrame.from_records(arr, index=index[:-1])