`.as_matrix()` removed from pandas now is `.values()`

Hi,

It looks like as_matrix() has been deprecated since pandas 0.23 and finally been removed.

Would you be open to a pull request that update the code, and if so will you publish an updated version on PyPI ?

Thanks.

Hi Carreau,

You can replace as_matrix() by .values() and keep the all code

You can replace as_matrix() by .values() and keep the all code

Yes, that's what my title say, but the code here does use .as_matrix() in the test and example. I'm asking if it's ok to send a PR to update.

Yes, i'm sorry. I didn't read the title..