Avoid crash in iframe renderers when running outside iPython

[mpaolini]

when running

echo '{"hour":"2019-01-01T00:00:00Z","perf":1}' | python <(                     
echo "                                                                                                                        
import pandas as pd                                                                                                           
from plotly import express as px                                                                                              
import sys                                                                                                                    
data = pd.read_json(sys.stdin.read(), lines=True, convert_dates=['hour'])                                                     
fig = px.line(data, x='hour', y='perf')                                                                                       
fig.show(renderer='iframe')                                                                                                   
")

if ipython is not installed you get:

Traceback (most recent call last):
  File "/dev/fd/63", line 7, in <module>
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/basedatatypes.py", line 2658, in show
    return pio.show(self, *args, **kwargs)
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_renderers.py", line 376, in show
    bundle = renderers._build_mime_bundle(fig_dict, renderers_string=renderer, **kwargs)
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_renderers.py", line 296, in _build_mime_bundle
    bundle.update(renderer.to_mimebundle(fig_dict))
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_base_renderers.py", line 564, in to_mimebundle
    filename = self.build_filename()
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_base_renderers.py", line 601, in build_filename
    ip = IPython.get_ipython()
AttributeError: 'NoneType' object has no attribute 'get_ipython'

if instead ipython is installed

Traceback (most recent call last):
  File "/dev/fd/63", line 7, in <module>
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/basedatatypes.py", line 2658, in show
    return pio.show(self, *args, **kwargs)
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_renderers.py", line 376, in show
    bundle = renderers._build_mime_bundle(fig_dict, renderers_string=renderer, **kwargs)
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_renderers.py", line 296, in _build_mime_bundle
    bundle.update(renderer.to_mimebundle(fig_dict))
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_base_renderers.py", line 564, in to_mimebundle
    filename = self.build_filename()
  File "/home/marco/src/plotly.py/packages/python/plotly/plotly/io/_base_renderers.py", line 602, in build_filename
    cell_number = list(ip.history_manager.get_tail(1))[0][1] + 1
AttributeError: 'NoneType' object has no attribute 'history_manager'

[jonmmease]

Hi @mpaolini, thanks for the PR. I'm happy to merge these changes, but I would like to understand your usecase a little better. Is the iframe renderer useful for you when running outside of IPython?

[mpaolini]

Hi, yes I use it in some “headless” scripts (as the one above) to generate charts programmatically . Ipython is not required in this scenarios , and often it is not installed for this reason.

Furthermore Ipython does not work well with <() bash redirection because it does not recognise the temporary file as a python script. So the above command only works on vanilla python

hope this clarifies it

[jonmmease]

Hi @mpaolini, sorry for the delay. Are you aware of the plotly.io.write_html function? This is the generally recommended way to export figures to HTML files. But again, no harm in avoiding crash here. Thanks for the PR!