Move irregular to xarray interface

holoviews/core/data/grid.py

@@ -172,6 +172,7 @@ def concat_dim(cls, datasets, dim, vdims):
     def irregular(cls, dataset, dim):
         return dataset.data[dimension_name(dim)].ndim > 1
 
+
     @classmethod
     def isscalar(cls, dataset, dim):
         values = cls.values(dataset, dim, expanded=False)

holoviews/core/data/xarray.py

@@ -275,6 +275,12 @@ def validate(cls, dataset, vdims=True):
                                 "following kdims were found to have "
                                 "non-matching array dimensions:\n\n%s"
                                 % ('\n'.join(nonmatching)), cls)
+    @classmethod
+    def irregular(cls, dataset, dim):
+        if dataset.data[dimension_name(dim)].ndim > 1:
+            return True
+        dim_name = dimension_name(dim)
+        return dim_name not in dataset.data.dims and dim_name in dataset.data.coords
 
     @classmethod
     def compute(cls, dataset):
@@ -410,8 +416,7 @@ def values(cls, dataset, dim, expanded=True, flat=True, compute=True, keep_index
                 data = data.data
         irregular = cls.irregular(dataset, dim) if dim in dataset.kdims else False
         irregular_kdims = [d for d in dataset.kdims if cls.irregular(dataset, d)]
-        non_dimensinal_dim = hasattr(dataset.data, 'dims') and dimension_name(dim) not in dataset.data.dims
-        if irregular_kdims or non_dimensinal_dim:
+        if irregular_kdims:
             virtual_coords = list(dataset.data[irregular_kdims[0].name].coords.dims)
         else:
             virtual_coords = []