Switch AlignmentError -> ValueError

Author: shoyer

doc/api.rst

@@ -485,7 +485,6 @@ Exceptions
 .. autosummary::
    :toctree: generated/
 
-   AlignmentError
    MergeError
 
 Advanced API

doc/whats-new.rst

@@ -130,7 +130,7 @@ Enhancements
   `Vincent Noel <https://github.com/vnoel>`_.
 
 - :py:func:`~xarray.align` now supports ``join='exact'``, which raises
-  :py:class:`~xarray.AlignmentError` instead of aligning when indexes to be
+  :py:class:`~xarray.ValueError` instead of aligning when indexes to be
   aligned are not equal.
   By `Stephan Hoyer <https://github.com/shoyer>`_.
 

xarray/__init__.py

@@ -2,7 +2,7 @@
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
-from .core.alignment import AlignmentError, align, broadcast, broadcast_arrays
+from .core.alignment import align, broadcast, broadcast_arrays
 from .core.common import full_like, zeros_like, ones_like
 from .core.combine import concat, auto_combine
 from .core.extensions import (register_dataarray_accessor,

xarray/core/alignment.py

@@ -15,10 +15,6 @@
 from .variable import Variable, IndexVariable
 
 
-class AlignmentError(Exception):
-    """Error for when an operation cannot be done with non-aligned objects."""
-
-
 def _get_joiner(join):
     if join == 'outer':
         return functools.partial(functools.reduce, operator.or_)
@@ -62,8 +58,8 @@ def align(*objects, **kwargs):
         - 'inner': use the intersection of object indexes
         - 'left': use indexes from the first object with each dimension
         - 'right': use indexes from the last object with each dimension
-        - 'exact': raise `xarray.AlignmentError` instead of aligning when
-          indexes to be aligned are not equal
+        - 'exact': instead of aligning, raise `ValueError` when indexes to be
+          aligned are not equal
     copy : bool, optional
         If ``copy=True``, data in the return values is always copied. If
         ``copy=False`` and reindexing is unnecessary, or can be performed with
@@ -131,7 +127,7 @@ def align(*objects, **kwargs):
                     for other in matching_indexes[1:]) or
                     dim in unlabeled_dim_sizes):
                 if join == 'exact':
-                    raise AlignmentError(
+                    raise ValueError(
                         'indexes along dimension {!r} are not equal'
                         .format(dim))
                 index = joiner(matching_indexes)

xarray/core/computation.py

@@ -599,8 +599,8 @@ def apply_ufunc(func, *args, **kwargs):
         - 'inner': use the intersection of object indexes
         - 'left': use indexes from the first object with each dimension
         - 'right': use indexes from the last object with each dimension
-        - 'exact': raise `xarray.AlignmentError` instead of aligning when
-          indexes to be aligned are not equal
+        - 'exact': raise `ValueError` instead of aligning when indexes to be
+          aligned are not equal
     dataset_join : {'outer', 'inner', 'left', 'right'}, optional
         Method for joining variables of Dataset objects with mismatched
         data variables.

xarray/core/ops.py

@@ -133,8 +133,8 @@ def fillna(data, other, join="left", dataset_join="left"):
         - 'inner': use the intersection of object indexes
         - 'left': use indexes from the first object with each dimension
         - 'right': use indexes from the last object with each dimension
-        - 'exact': raise `xarray.AlignmentError` instead of aligning when
-          indexes to be aligned are not equal
+        - 'exact': raise `ValueError` instead of aligning when indexes to be
+          aligned are not equal
     dataset_join : {'outer', 'inner', 'left', 'right'}, optional
         Method for joining variables of Dataset objects with mismatched
         data variables.

xarray/tests/test_dataset.py

@@ -1251,7 +1251,7 @@ def test_align_exact(self):
         self.assertDatasetIdentical(left1, left)
         self.assertDatasetIdentical(left2, left)
 
-        with self.assertRaises(xr.AlignmentError):
+        with self.assertRaisesRegexp(ValueError, 'indexes .* not equal'):
             xr.align(left, right, join='exact')
 
     def test_align_exclude(self):

xarray/tests/test_merge.py

@@ -66,7 +66,7 @@ def test_merge_error(self):
     def test_merge_alignment_error(self):
         ds = xr.Dataset(coords={'x': [1, 2]})
         other = xr.Dataset(coords={'x': [2, 3]})
-        with self.assertRaises(xr.AlignmentError):
+        with self.assertRaisesRegexp(ValueError, 'indexes .* not equal'):
             xr.merge([ds, other], join='exact')
 
     def test_merge_no_conflicts_single_var(self):