Nothing displaying in Jupyter

Panel
1

I tried following the docs but cannot get anything to display in Jupyter; I just get an empty output. This is the code I am trying:

%matplotlib inline
import pandas as pd
import panel as pn
pn.extension()
import panel.widgets as pnw

window = pnw.IntSlider(name=‘window’, value=10, start=1, end=60)

@pn.depends(window)
def reactive_trends(window):
return pd.DataFrame([{‘a’: 1, ‘b’: 2}, {‘a’:3, ‘b’: 4}])

widgets = pn.Column(“
\n# Filter”, window)
trends = pn.Row(reactive_trends, widgets)
trends

I assume I’m missing something obvious here?

2

I tried a sample notebook and have the same problem. Looking at the JS console I see complaints about BokehJS not being found, even though I have bokeh installed in my environment.

I searched around, and found a suggestion to add:

from bokeh.plotting import output_notebook, figure, show

output_notebook(hide_banner=True)

However, then I got a whole lot of errors about:

Access to script at ‘https://cdn.bokeh.org/bokeh/release/bokeh-widgets-2.3.0.min.js’ from origin ‘http://localhost:8888’ has been blocked by CORS policy: No ‘Access-Control-Allow-Origin’ header is present on the requested resource.

It looks like this was supposed to be fixed in 0.10.4 but it seems that hasn’t been released. Then again, I tried with panel 0.11.0rc5 and had the same empty output.

1 Like
3

Try using panel 0.10.3 and bokeh 2.2.3.

You might also need to clear the notebook output, save, close the browser, reopen and hard refresh to make it use those versions.

A Panel released 0.11 should be arriving any day now.

4

I installed those, and shut down and restarted Jupyter, and now I get:

AttributeError: module 'panel' has no attribute 'extension'

and likewise for interact.

Note: I am using pip, not conda.

It seems like if I use .show() then things work, so that will unblock me for now.

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5

You would need to provide more information in the form of a minimum, reproducible example to allow further investigation. And add in screen shots as well.

6

image
image2282×1116 199 KB

Those pip messages are weird and may have something to do with it. Something very weird is going on, because I have two notebooks open from the same instance of Jupyter, and the one is doing this, and the other one is working (as long as I use show()). Both show the same versions of panel and bokeh (plus that weird error), but they are in different venvs. I wouldn’t worry too much about it as I have one working environment and this must be something screwy with the other one.

What would be useful to me would be a way to log to the browser console when using show(). I saw some ways of adding JS in callbacks but is there a more direct way? I find things work for me once and then seem to stop (e.g. if I have a dynamically updating set of options in a picker, it updates once and then never again), that logging would really help with.I tried using a static text widget but that stops updating too.

(Edit: it looks like just adding “import logging” helped here; I now see exceptions in my notebook output).

7

I wrote the following below, but when I was almost finished a thought occurred - do you have a panel.py file in the folder? This will take priority over the package and give this kind of error.

A better way to check the version number is proberly using pn.__version__ and bokeh.__version__. The pip command can sometimes be from another environment depending on OS/environment manager.

If you cannot do that, try to see if the panel file is located where you expect it to be with the following:

import panel as pn
import inspect

inspect.getfile(pn)

The small error from the pip commands look like something went wrong during a local panel install, maybe from a misspelling.

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8

I don’t have a panel.py. I managed to get things working as long as I stick to the one venv. My last struggle is trying to deploy; I added a .servable() call to the penultimate cell in my notebook, but when I run “panel serve” from the CLI and open the URL displayed by the Bokeh server I get 404s.

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9

Could you provide a screenshot with as much information as possible?

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10

Not much to see, really. Here’s the browser:

image
image1172×208 25.2 KB

12

The browser is Firefox; pasting the URL in Chrome replaced the spaces with %20s but had the same result so I don’t think that’s the issue, but let me try.

Edit: and yes, it looks like the spaces were causing a problem! Yay! Thank goodness I don’t have to go learn Plotly :wink: Thanks all! Off to Dockerize.

1 Like