Metric Integers - Python

metric.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import math

class MetricInt(int):
    """
        Integer with metric string representation.
    """
    incPrefixes = ['k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']
    decPrefixes = ['m', 'µ', 'n', 'p', 'f', 'a', 'z', 'y']

    def __str__(self):
        """
            Convert integer to metric string.
            http://stackoverflow.com/a/15734251/1695680
        """
        d = self
        if self == 0:
            return str(0)
        degree = int(math.floor(math.log10(math.fabs(d)) / 3))

        prefix = ''

        if degree!=0:
            ds = degree/math.fabs(degree)
            if ds == 1:
                if degree - 1 < len(self.incPrefixes):
                    prefix = self.incPrefixes[degree - 1]
                else:
                    prefix = self.incPrefixes[-1]
                    degree = len(self.incPrefixes)

            elif ds == -1:
                if -degree - 1 < len(self.decPrefixes):
                    prefix = self.decPrefixes[-degree - 1]
                else:
                    prefix = self.decPrefixes[-1]
                    degree = -len(self.decPrefixes)

            scaled = float(d * math.pow(1000, -degree))

            s = "{scaled} {prefix}".format(scaled=scaled, prefix=prefix)

        else:
            s = "{d}".format(d=int(d))

        return(s)

I like the name "metric".
Maybe a very minimal pip package could be a good idea.

if you never did a package before you can have a look at 2 of my projects
https://github.com/scls19fr/openweathermap_requests
https://github.com/scls19fr/pandas_degreedays

Add some unit tests and ensure that it also works fine with several Python version
(Travis can help)

if I were you I will keep ToSI a function and provide MetricInt, MetricFloat, MetricDouble, MetricDecimal.

Adding units could be a great idea.
But maybe we should see with Pint http://pint.readthedocs.org/

see hgrecco/pint#237