Support for 'no_conflicts', 'broadcast_equals' in concat.

xarray/core/concat.py

@@ -5,6 +5,7 @@
 
 from . import utils, dtypes
 from .alignment import align
+from .merge import broadcast_dimension_size
 from .variable import IndexVariable, Variable, as_variable
 from .variable import concat as concat_vars
 
@@ -145,7 +146,13 @@ def concat(
             "`data_vars` and `coords` arguments"
         )
 
-    if compat not in ["equals", "identical", "override", "no_conflicts"]:
+    if compat not in [
+        "equals",
+        "identical",
+        "override",
+        "no_conflicts",
+        "broadcast_equals",
+    ]:
         raise ValueError(
             "compat=%r invalid: must be 'equals', 'identical or 'override'" % compat
         )
@@ -186,7 +193,7 @@ def _calc_concat_dim_coord(dim):
     return dim, coord
 
 
-def _calc_concat_over(datasets, dim, data_vars, coords):
+def _calc_concat_over(datasets, dim, data_vars, coords, compat):
     """
     Determine which dataset variables need to be concatenated in the result,
     and which can simply be taken from the first dataset.
@@ -225,14 +232,18 @@ def process_subset_opt(opt, subset):
                         for ds_rhs in datasets[1:]:
                             v_rhs = ds_rhs.variables[k].compute()
                             computed.append(v_rhs)
-                            if not v_lhs.equals(v_rhs):
+                            if not getattr(v_lhs, compat)(v_rhs):
                                 concat_over.add(k)
                                 equals[k] = False
                                 # computed variables are not to be re-computed
                                 # again in the future
                                 for ds, v in zip(datasets[1:], computed):
                                     ds.variables[k].data = v.data
                                 break
+                            elif compat == "broadcast_equals":
+                                # (REMOVE): This is from merge.unique_variable
+                                dim_lengths = broadcast_dimension_size(computed)
+                                v_lhs = v_lhs.set_dims(dim_lengths)
                         else:
                             equals[k] = True
 
@@ -291,7 +302,7 @@ def _dataset_concat(
         *datasets, join=join, copy=False, exclude=[dim], fill_value=fill_value
     )
 
-    concat_over, equals = _calc_concat_over(datasets, dim, data_vars, coords)
+    concat_over, equals = _calc_concat_over(datasets, dim, data_vars, coords, compat)
 
     def insert_result_variable(k, v):
         assert isinstance(v, Variable)
@@ -338,7 +349,7 @@ def insert_result_variable(k, v):
                     is_equal = equals[k]
                 except KeyError:
                     result_vars[k].load()
-                    is_equal = v.equals(result_vars[k])
+                    is_equal = getattr(v, compat)(result_vars[k])
                 if not is_equal:
                     raise ValueError(
                         "Variable '%s' is not equal across datasets. "