make irregaluar if non-dimensional coordinate

Author: hoxbro

holoviews/core/data/grid.py

@@ -170,7 +170,7 @@ def concat_dim(cls, datasets, dim, vdims):
 
     @classmethod
     def irregular(cls, dataset, dim):
-        return dataset.data[dimension_name(dim)].ndim > 1
+        return dataset.data[dimension_name(dim)].ndim > 1 or dimension_name(dim) not in dataset.data.dims
 
 
     @classmethod