Merge pull request #698 from SixtyCapital/allow-empty-dfs

Allow empty DataFrame in Dataset construction

Author: shoyer

xray/core/dataset.py

@@ -1788,11 +1788,8 @@ def from_dataframe(cls, dataframe):
                 obj[dim] = (dim, lev)
             shape = [lev.size for lev in idx.levels]
         else:
-            if idx.size:
-                dims = (idx.name if idx.name is not None else 'index',)
-                obj[dims[0]] = (dims, idx)
-            else:
-                dims = []
+            dims = (idx.name if idx.name is not None else 'index',)
+            obj[dims[0]] = (dims, idx)
             shape = -1
 
         for name, series in iteritems(dataframe):

xray/test/test_dataset.py

@@ -1639,9 +1639,16 @@ def test_to_and_from_dataframe(self):
 
         df = pd.DataFrame()
         actual = Dataset.from_dataframe(df)
-        expected = Dataset()
+        expected = Dataset(coords={'index':[]})
         self.assertDatasetIdentical(expected, actual)
 
+        # GH697
+        df = pd.DataFrame({'A' : []})
+        actual = Dataset.from_dataframe(df)
+        expected = Dataset({'A': DataArray([], dims=('index',))})
+        self.assertDatasetIdentical(expected, actual)
+
+
         # regression test for GH278
         # use int64 to ensure consistent results for the pandas .equals method
         # on windows (which requires the same dtype)