Fix issue in solution to xarray conversion

sunode/problem.py

@@ -107,34 +107,38 @@ def solution_to_xarray(  # type: ignore
         solution = solution.view(self.state_dtype)[..., 0]
         params = self.extract_params(user_data)
 
-        def as_dict(array, prepend=None):  # type: ignore
+        def as_dict(array, dims, prepend=None):  # type: ignore
             if prepend is None:
                 prepend = []
             dtype = array.dtype
             out = {}
             for name in dtype.names:
                 if array[name].dtype == np.float64:
-                    out['_'.join(prepend + [name])] = array[name]
+                    out['_'.join(prepend + [name])] = (tuple(dims[name][1]), array[name])
                 else:
-                    out.update(as_dict(array[name], prepend + [name]))
+                    out.update(as_dict(array[name], dims[name], prepend + [name]))
             return out
 
-        data = xr.Dataset()
+        data = xr.Dataset(coords=self.coords)
         data['time'] = ('time', tvals)
         #  TODO t0?
         if unstack_state:
-            state = as_dict(solution, ['solution'])
+            state = as_dict(solution, self.state_subset.dims, ['solution'])
             for name in state:
-                assert name not in data
-                data[name] = ('time', state[name])
+                if name in data:
+                    raise ValueError(f"Variable {name} is not unique.")
+                dims, vals = state[name]
+                data[name] = (('time',) + dims, vals)
         else:
             data['solution'] = ('time', solution)
 
         if unstack_params:
-            params = as_dict(params, ['parameters'])
+            params = as_dict(params, self.params_subset.dims, ['parameters'])
             for name in params:
-                assert name not in data
-                data[name] = params[name]
+                if name in data:
+                    raise ValueError(f"Variable {name} is not unique.")
+                dims, vals = params[name]
+                data[name] = (dims, vals)
         else:
             data['parameters'] = params