Performance issue

[Kanatoko]

Current version is rather slow. I'm new to python and don't know how to write effective python program.
(Maybe I should avoid nested for loops and use numpy instead?)

[rtmlp]

I am going through your code and can definitely work on to improving the speed using numpy

[Kanatoko]

That is really great. This code is just a translation from Java to Python, line by line.
I use only Java on my production environment, so I don't have a motivation for speeding up this python version.
I'm waiting for your pull request. Thank you.