Rasa setting a platform specific matplotlib backend fails

[elyase]

Rasa version:
1.4.0

Python version:
3.7.4

Operating system (windows, osx, ...):
Linux Ubuntu 18.04.3 LTS

Issue:
Rasa tries to set a matplotlib backend which is environment specific (and IMO also unnecessary) and fails in headless environments. According to matplotlib docs:

Likewise, the Tk framework (TkAgg backend) does not require any external dependencies and is normally always available. On certain Linux distributions, a package named python-tk (or similar) needs to be installed.

I think this line is the culprit and would be best to just delete it as it is not clear what the motivation is for that line anymore (seems to be based on an old OSX specific issue).

rasa/rasa/core/test.py

Lines 19 to 21 in 5119efc

	import matplotlib
	matplotlib.use("TkAgg")

In addition it would be better if matplotlib is imported inside the function call and not module wide (see here for rationale).

Error (including full traceback):

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
~/test/test-testsuite/source/initializer/tests/test_datapoint.py in 
----> 1 from rasa.core.interpreter import RegexInterpreter

~/miniconda3/envs/test/lib/python3.7/site-packages/rasa/__init__.py in 
      7 
      8 from rasa.run import run
----> 9 from rasa.train import train
     10 from rasa.test import test
     11 

~/miniconda3/envs/test/lib/python3.7/site-packages/rasa/train.py in 
      5 from typing import Text, Optional, List, Union, Dict
      6 
----> 7 from rasa.importers.importer import TrainingDataImporter
      8 from rasa import model
      9 from rasa.core.domain import Domain

~/miniconda3/envs/test/lib/python3.7/site-packages/rasa/importers/importer.py in 
      5 
      6 from rasa.core.domain import Domain
----> 7 from rasa.core.interpreter import RegexInterpreter, NaturalLanguageInterpreter
      8 from rasa.core.training.structures import StoryGraph
      9 from rasa.nlu.training_data import TrainingData

~/miniconda3/envs/test/lib/python3.7/site-packages/rasa/core/__init__.py in 
      4 
      5 from rasa.core.train import train
----> 6 from rasa.core.test import test
      7 from rasa.core.visualize import visualize
      8 

~/miniconda3/envs/test/lib/python3.7/site-packages/rasa/core/test.py in 
     19 import matplotlib
     20 
---> 21 matplotlib.use("TkAgg")
     22 
     23 logger = logging.getLogger(__name__)

~/miniconda3/envs/test/lib/python3.7/site-packages/matplotlib/cbook/deprecation.py in wrapper(*args, **kwargs)
    305                 f"for the old name will be dropped %(removal)s.")
    306             kwargs[new] = kwargs.pop(old)
--> 307         return func(*args, **kwargs)
    308 
    309     # wrapper() must keep the same documented signature as func(): if we

~/miniconda3/envs/test/lib/python3.7/site-packages/matplotlib/__init__.py in use(backend, warn, force)
   1307         if force:
   1308             from matplotlib.pyplot import switch_backend
-> 1309             switch_backend(name)
   1310     else:
   1311         # Finally if pyplot is not imported update both rcParams and

~/miniconda3/envs/test/lib/python3.7/site-packages/matplotlib/pyplot.py in switch_backend(newbackend)
    234                 "Cannot load backend {!r} which requires the {!r} interactive "
    235                 "framework, as {!r} is currently running".format(
--> 236                     newbackend, required_framework, current_framework))
    237 
    238     rcParams['backend'] = rcParamsDefault['backend'] = newbackend

ImportError: Cannot load backend 'TkAgg' which requires the 'tk' interactive framework, as 'headless' is currently running

Command or request that led to error:

from rasa.core.interpreter import RegexInterpreter

# or more directly

from rasa.core.test import test

[sara-tagger]

Thanks for the issue, @Ghostvv will get back to you about it soon!

You may find help in the docs and the forum, too 🤗

[tabergma]

@elyase Thanks for raising the issue. In general we are open to making matplotlib optional.

I added the lines back then in rasa/core/test, but cannot remember the exact reason. I just tried to run rasa test nlu (which plots some graphs) without those lines and it was working fine for me. So, I guess we can do as you suggested.

Do you want to clean it up by yourself and create a PR for it?

[stale]

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[stale]

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