Improved bokeh json patch computation

Improved code that tidies up bokeh json patches to update plots.
Should result in an overall reduction of 30-50% in the json size

holoviews/plotting/bokeh/util.py

@@ -1,6 +1,7 @@
+import itertools
 from distutils.version import LooseVersion
-
 from collections import defaultdict
+
 import numpy as np
 
 try:
@@ -40,13 +41,9 @@
 # and can therefore be safely ignored. Axes currently fail saying
 # LinearAxis.computed_bounds cannot be updated
 IGNORED_MODELS = ['LinearAxis', 'LogAxis', 'DatetimeAxis',
-                  'CategoricalAxis' 'BasicTicker', 'BasicTickFormatter',
+                  'CategoricalAxis', 'BasicTicker', 'BasicTickFormatter',
                   'FixedTicker', 'FuncTickFormatter', 'LogTickFormatter']
 
-# Where to look for the ignored models
-LOCATIONS = ['new', 'below', 'right', 'left',
-             'renderers', 'above', 'attributes', 'plot', 'ticker']
-
 # Model priority order to ensure some types are updated before others
 MODEL_PRIORITY = ['Range1d', 'Title', 'Image', 'LinearColorMapper',
                   'Plot', 'Range1d', 'LinearAxis', 'ColumnDataSource']
@@ -95,7 +92,7 @@ def mpl_to_bokeh(properties):
         if k == 's':
             new_properties['size'] = v
         elif k == 'marker':
-            new_properties.update(markers.get(v, {'marker': v}))
+            new_properties.updates(markers.get(v, {'marker': v}))
         elif k == 'color' or k.endswith('_color'):
             with abbreviated_exception():
                 v = colors.ColorConverter.colors.get(v, v)
@@ -176,22 +173,40 @@ def refs(json):
     return result
 
 
-def compute_static_patch(document, models, json=None):
+def get_ids(obj):
+    """
+    Returns a list of all ids in the supplied object.
+    Useful for determining if a json representation contains
+    references to other objects.
+    """
+    ids = []
+    if isinstance(obj, list):
+        ids = [get_ids(o) for o in obj]
+    elif isinstance(obj, dict):
+        ids = [(v,) if k == 'id' else get_ids(v)
+               for k, v in obj.items()]
+    return list(itertools.chain(*ids))
+
+
+def compute_static_patch(document, models):
     """
     Computes a patch to update an existing document without
     diffing the json first, making it suitable for static updates
     between arbitrary frames. Note that this only supports changed
     attributes and will break if new models have been added since
     the plot was first created.
     """
-    references = refs(json if json else document.to_json())
-    requested_updates = [m.ref['id'] for m in models]
+    references = refs(document.to_json())
+    model_ids = [m.ref['id'] for m in models]
 
+    requested_updates = []
     value_refs = {}
     events = []
     update_types = defaultdict(list)
     for ref_id, obj in references.items():
-        if ref_id not in requested_updates:
+        if ref_id in model_ids:
+            requested_updates += get_ids(obj)
+        else:
             continue
         if obj['type'] in MODEL_PRIORITY:
             priority = MODEL_PRIORITY.index(obj['type'])
@@ -203,16 +218,17 @@ def compute_static_patch(document, models, json=None):
                                                          value_refs)
             events.append((priority, event))
             update_types[obj['type']].append(key)
-    events = [delete_refs(e, LOCATIONS, IGNORED_MODELS)
+    events = [delete_refs(e, IGNORED_MODELS)
               for _, e in sorted(events, key=lambda x: x[0])]
-    value_refs = {ref_id: delete_refs(val, LOCATIONS, IGNORED_MODELS)
+    events = [e for e in events if all(i in requested_updates for i in get_ids(e))]
+    value_refs = {ref_id: delete_refs(val, IGNORED_MODELS)
                   for ref_id, val in value_refs.items()}
     references = [val for val in value_refs.values()
-                  if val is not None]
+                  if val not in [None, {}]]
     return dict(events=events, references=references)
 
 
-def delete_refs(obj, locs, delete):
+def delete_refs(obj, delete):
     """
     Delete all references to specific model types by recursively
     traversing the object and looking for the models to be deleted in
@@ -226,15 +242,14 @@ def delete_refs(obj, locs, delete):
             return None
         new_obj = {}
         for k, v in list(obj.items()):
-            if k in locs:
-                ref = delete_refs(v, locs, delete)
-                if ref is not None:
-                    new_obj[k] = ref
-            else:
-              new_obj[k] = v
+            if k in ['data', 'palette'] or (k == 'attributes' and not get_ids(v)):
+                continue
+            ref = delete_refs(v, delete)
+            if ref is not None:
+                new_obj[k] = ref
         return new_obj
     elif isinstance(obj, list):
-        objs = [delete_refs(v, locs, delete) for v in obj]
+        objs = [delete_refs(v, delete) for v in obj]
         return [o for o in objs if o is not None]
     else:
         return obj