Violin plot support

[alanocallaghan]

Close #62

[daattali]

Thank you, I'll take a look and merge on the weekend. If you'd like, you can also add violin to the function documentation, examples, and a unit test

[alanocallaghan]

I'll do the above today. Cheers

[alanocallaghan]

Done, I also re-ran devtools::document(). I get one failing test and one warning seemingly due to a missing file

[daattali]

Hey, sorry for taking so long, I finally took a look. Thanks for adding the documentation!

One last thing is that the tests need to pass. I see you added a test for violin plot, but I don't see the associated expected image. For any visual test there's an expected image (see https://github.com/daattali/ggExtra/tree/master/tests/figs/ggMarginal) so that the test will be able to compare. Could you add the expected images for this? @crew102 can weigh in on how to generate them if you don't know

[alanocallaghan]

Thanks Dean.

I wasn't quite sure how the comparison of images worked (never seen tests laid out like this before) & thought maybe the tests would just pass on your machine. I've rendered them it out, but as noted in the commit message it also updated an unrelated file in the ggplot2-latest folder

By the way, why is the environment variable named RunGgplot2Tests=yes with a value of "yes", rather than RunGgplot2Tests? I don't think I can create a variable of that name on my Linux box

[daattali]

@alanocallaghan thanks for the quick job! As for the env variable, that's a good question, and you're right I think it was an error.