Allowed NdMappings with no kdims

holoviews/core/ndmapping.py

@@ -573,6 +573,8 @@ def __getitem__(self, indexslice):
                 raise IndexError("Boolean index must match length of sliced object")
             selection = zip(indexslice, self.data.items())
             return self.clone([item for c, item in selection if c])
+        elif indexslice == () and not self.kdims:
+            return self.data[()]
         elif indexslice in [Ellipsis, ()]:
             return self
         elif Ellipsis in wrap_tuple(indexslice):

holoviews/core/util.py

@@ -888,7 +888,9 @@ def get_dynamic_item(map_obj, dimensions, key):
     and a corresponding key. The dimensions must be a subset
     of the map_obj key dimensions.
     """
-    if isinstance(key, tuple):
+    if key == () and not dimensions:
+        return key, map_obj[()]
+    elif isinstance(key, tuple):
         dims = {d.name: k for d, k in zip(dimensions, key)
                 if d in map_obj.kdims}
         key = tuple(dims.get(d.name) for d in map_obj.kdims)

holoviews/plotting/renderer.py

@@ -202,7 +202,8 @@ def _validate(self, obj, fmt):
 
         if fmt in ['auto', None]:
             if ((len(plot) == 1 and not plot.dynamic)
-                or (len(plot) > 1 and self.holomap is None)):
+                or (len(plot) > 1 and self.holomap is None) or
+                (plot.dynamic and len(plot.keys[0]) == 0)):
                 fmt = fig_formats[0] if self.fig=='auto' else self.fig
             else:
                 fmt = holomap_formats[0] if self.holomap=='auto' else self.holomap