Plotly offline will not work upon page reload or from another client; will not work with ipywidgets

[aggFTW]

Hi,

We found out that the following PR: #379
ends up breaking plotly offline on page refreshes.

Upon first execution:

And upon refresh:

It seems like what we really should do is have an if statement on javascript that re-registers Plotly.

At the same time, if we want to use plotly with ipywidgets in an output widget, that check on __PLOTLY_OFFLINE_INITIALIZED in that PR would make it impossible to re-register Plotly from init_notebook_mode by any other browser connected to the same kernel or the same browser on a refresh. Again, this check to not re-register should be done on the javascript side, because it is the front end that knows whether Plotly is defined or not, not the server.

Thanks!
Alejandro

cc @msftristew @ellisonbg @tc0312

[aggFTW]

Cell 1:

from plotly.offline import init_notebook_mode
from plotly.graph_objs import Pie, Figure, Data
from plotly.offline import iplot

import plotly as plt
plt.__version__

Cell 2:

init_notebook_mode()

Cell 3:

data = [Pie(values=[1,2,3])]
fig = Figure(data=Data(data))
iplot(fig, show_link=False)

[aggFTW]

We suspect this is related: #458

[yankev]

@aggFTW Yea, it appears that removing the check for __PLOTLY_OFFLINE_INITIALIZED in PR #379, like you said, fixes the issue (edit: of reloading the notebook).

[aggFTW]

@yankev well, removing the check + adding the javascript if statement would be the right thing, it seems like. Are you working on it?

[yankev]

@aggFTW yep, @mdtusz and I are looking at it right now.

[aggFTW]

Ok, thanks! 😄

[aggFTW]

@tc0312 and I were looking at this and we think the python check should be removed and the javascript should look something like this (we haven't tested it):

display(HTML("<script type='text/javascript'>" +
    "if (typeof window.Plotly === 'undefined') {" +
    "define('plotly', function(require, exports, module) {" +
    "get_plotlyjs()" +
    "});" +
    "require(['plotly'], function(Plotly) {" +
    "window.Plotly = Plotly;" +
    "});" +
    "}" +
    "</script>"))

We hope it helps!

[mdtusz]

Yep! This PR will solve it - just cleaning up a few things then it will be merged in.

[msftristew]

Great stuff, thanks @mdtusz.