Cross incompatibility with altair and nteract vs classic notebook

Altair does not work in the classic Jupyter Notebook after successfully using it in an nteract web notebook.

Altair works in nteract without a user needing to run alt.renderers.enable('notebook'). e.g. this notebook works https://github.com/nteract/nteract/blob/master/applications/desktop/example-notebooks/altair.ipynb when launched with jupyter nteract.

When using Altair without nteract, a user must run alt.renderers.enable('notebook'). However, this returns the below error. As per the Altair troubleshooting guide, Altair believes Vega is not installed. Even upon verifying successful Altair + Vega installation (as per the installation guide ), the error persists. conda list verified Vega is installed. I am using Jupyter Notebook 5.6.0.

Do you know what may be causing this? cc @rgbkrk

---------------------------------------------------------------------------
NoSuchEntryPoint                          Traceback (most recent call last)
~/anaconda3/lib/python3.6/site-packages/altair/utils/plugin_registry.py in _enable(self, name, **options)
    133             try:
--> 134                 ep = entrypoints.get_single(self.entry_point_group, name)
    135             except entrypoints.NoSuchEntryPoint:

~/anaconda3/lib/python3.6/site-packages/entrypoints.py in get_single(group, name, path)
    185 
--> 186     raise NoSuchEntryPoint(group, name)
    187 

NoSuchEntryPoint: No 'notebook' entry point found in group 'altair.vegalite.v2.renderer'

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
<ipython-input-4-025c0cf17452> in <module>()
----> 1 alt.renderers.enable('notebook')

~/anaconda3/lib/python3.6/site-packages/altair/utils/plugin_registry.py in enable(self, name, **options)
    169         if name is None:
    170             name = self.active
--> 171         return PluginEnabler(self, name, **options)
    172 
    173 

~/anaconda3/lib/python3.6/site-packages/altair/utils/plugin_registry.py in __init__(self, registry, name, **options)
     23         self.options = options
     24         self.original_state = registry._get_state()
---> 25         self.registry._enable(name, **options)
     26 
     27     def __enter__(self):

~/anaconda3/lib/python3.6/site-packages/altair/utils/plugin_registry.py in _enable(self, name, **options)
    135             except entrypoints.NoSuchEntryPoint:
    136                 if name in self.entrypoint_err_messages:
--> 137                     raise ValueError(self.entrypoint_err_messages[name])
    138                 else:
    139                     raise

ValueError: 
To use the 'notebook' renderer, you must install the vega package
and the associated Jupyter extension.
See https://altair-viz.github.io/getting_started/installation.html
for more information.

[jakevdp]

You need to pip install vega==1.3. vega version 2.0 does not work with the current release of Altair. See #1114

[jakevdp]

When the plots are interactive, do you store the changed result?

No, the PNG is rendered at the time the plot is displayed. You can see the source here: https://github.com/vega/ipyvega/blob/master/src/index.ts#L22-L35