Add LaTeX repr for distributions

[fonnesbeck]

This PR adds LaTeX output when distributions are shown in Jupyter notebooks. The initial commit has this implemented for all continuous variables. Discrete, MV to come.

[twiecki]

how about new-style r'{}'.format(...)? https://pyformat.info/

[fonnesbeck]

The new style does not like strings with curly braces in them. This was easier.

[fonnesbeck]

OK, figured it out.

[fonnesbeck]

Odd failures related to multiprocessing in 2.7.

[ghost]

The failures occur because of usage functools.partial with bound method as an argument.

Multiprocessing tries to pickle resulting function objects, but fails because bound methods are not pickleable in Python 2, although they are pickleable in Python 3. For example, this code works with Python 3, but not Python 2:

import pickle
class Foo:
    def bar(self):
        return 3
pickle.dumps(Foo().bar)

I tried to replace invocations of functools.partial by direct implementations of _repr_latex_ method in my fork and the tests seem to work there.

[twiecki]

Thanks @a-rodin. The best approach is to do a PR onto this PR (specifically, the latex_dists branch) with your fixes.

[twiecki]

I think these should not be here, not quite sure.

[twiecki]

Looks like the whitespaces are still there.

[fonnesbeck]

It appears that My Favorite Text Editor sucks at whitespace removal, even inserting it in some places it did not exist.

[fonnesbeck]

Should be good to go now.

[ColCarroll]

would this be reasonable to propagate to models and maybe even the traces? It looks like it is more work than '\n'.join([repr(v) for v in self.vars]).

[fonnesbeck]

I think having a _repr_latex_ for a model would be a great idea. Would be a nice way to get an overview of the model, particularly if it is built up over a number of cells.

[ferrine]

vote for renaming _repr_latex_ to __latex__. The reason is that single leading underscore denotes private attributes and methods. But _latex_repr_ is not private at all. As for __latex__ it is our magic.

[fonnesbeck]

We aren’t at liberty to change it because they are hooks used by IPython. If you change the name they won’t work.