Iterate over data_vars only (#2506)

* iterate over data_vars

* whats new

Author: max-sixty

doc/whats-new.rst

@@ -33,6 +33,9 @@ v0.11.0 (unreleased)
 Breaking changes
 ~~~~~~~~~~~~~~~~
 
+- Iterating over a ``Dataset`` now includes only data variables, not coordinates.
+  Similarily, calling ``len`` and ``bool`` on a ``Dataset`` now  
+  includes only data variables
 - Xarray's storage backends now automatically open and close files when
   necessary, rather than requiring opening a file with ``autoclose=True``. A
   global least-recently-used cache is used to store open files; the default

xarray/core/dataset.py

@@ -930,32 +930,13 @@ def __contains__(self, key):
         return key in self._variables
 
     def __len__(self):
-        warnings.warn('calling len() on an xarray.Dataset will change in '
-                      'xarray v0.11 to only include data variables, not '
-                      'coordinates. Call len() on the Dataset.variables '
-                      'property instead, like ``len(ds.variables)``, to '
-                      'preserve existing behavior in a forwards compatible '
-                      'manner.',
-                      FutureWarning, stacklevel=2)
-        return len(self._variables)
+        return len(self.data_vars)
 
     def __bool__(self):
-        warnings.warn('casting an xarray.Dataset to a boolean will change in '
-                      'xarray v0.11 to only include data variables, not '
-                      'coordinates. Cast the Dataset.variables property '
-                      'instead to preserve existing behavior in a forwards '
-                      'compatible manner.',
-                      FutureWarning, stacklevel=2)
-        return bool(self._variables)
+        return bool(self.data_vars)
 
     def __iter__(self):
-        warnings.warn('iteration over an xarray.Dataset will change in xarray '
-                      'v0.11 to only include data variables, not coordinates. '
-                      'Iterate over the Dataset.variables property instead to '
-                      'preserve existing behavior in a forwards compatible '
-                      'manner.',
-                      FutureWarning, stacklevel=2)
-        return iter(self._variables)
+        return iter(self.data_vars)
 
     def __array__(self, dtype=None):
         raise TypeError('cannot directly convert an xarray.Dataset into a '

xarray/tests/test_dataset.py

@@ -420,16 +420,12 @@ def test_properties(self):
         assert isinstance(ds.dims.mapping, utils.SortedKeysDict)
         assert type(ds.dims.mapping.mapping) is dict  # noqa
 
-        with pytest.warns(FutureWarning):
-            assert list(ds) == list(ds.variables)
-        with pytest.warns(FutureWarning):
-            assert list(ds.keys()) == list(ds.variables)
+        assert list(ds) == list(ds.data_vars)
+        assert list(ds.keys()) == list(ds.data_vars)
         assert 'aasldfjalskdfj' not in ds.variables
         assert 'dim1' in repr(ds.variables)
-        with pytest.warns(FutureWarning):
-            assert len(ds) == 7
-        with pytest.warns(FutureWarning):
-            assert bool(ds)
+        assert len(ds) == 3
+        assert bool(ds)
 
         assert list(ds.data_vars) == ['var1', 'var2', 'var3']
         assert list(ds.data_vars.keys()) == ['var1', 'var2', 'var3']