Matplotlib as dependency of oemof in order to get examples running?

AFAIK oemof should be designed with less dependencies. But first-time users running example scripts stumble upon an ugly error message matplotlib is not installed.

Traceback (most recent call last):
  File "simple_least_costs/simple_least_costs.py", line 12, in <module>
    import matplotlib.pyplot as plt
ImportError: No module named 'matplotlib'

Sould we add matplotlib as dependency? Is there any other option available? @birgits how does extra_requires work? Would it be possible to apply this concept here?

[gplssm]

In order to make a quick decision until release, let’s up-/downvote this comment. I check on Monday 11 pm - sharp.

[gplssm]

Thanks for your feedback! There is a tendency to keep current work load small and keep matplotlib as dependency. With @uvchik last post, a “new” idea popped up. If you @oemof/oemof prefer to have matplotlib not in the dependency list and handle missing matplotlib installation as illustrated above, please upvote the above post.

Mid or long-term discussion about this topic should be continued until v0.1.1. Please use this issues #229