Port of https://github.com/thirtysixthspan/descriptive_statistics to python. 
I've encapsulated it in an Enum class as I wasn't intending to modify the original list.
My main use will be at https://github.com/gleicon/pymetrics package.

Install
    $ python setup install

Basic usage:

    from py_descriptive_statistics import Enum 
    enum = Enum([2,6,9,3,5,1,8,3,6,9,2])
                                                                                    
    print enum.number()                                                             
    print enum.sum()                                                                
    print enum.mean()                                                               
    print enum.median()                                                             
    print enum.variance()                                                           
    print enum.standard_deviation()                                                 
    print enum.percentile(70)                                                       
    print enum.percentile(95)                                                       
    print enum.percentile(99)

To run tests
    $ cd tests
    $ python pdstests.py