#! /usr/bin/python
# Save as test.py, then run
#
# My times:
#     sven1: 7.10525
#     sven2: 0.50151
#     liori: 1.15823
#    delnan: 2.17310
#      emil: 7.72502
#     steve: 0.72302

import random
import numpy
import itertools
import timeit

x = [random.random()>0.5 for i in xrange(1000)]

def sven1():
    return sum(2**i*b for i, b in enumerate(x))

def sven2():
    return numpy.sum(2**numpy.arange(len(x))*x)

def liori():
    return reduce(lambda a,b:2*a+b, reversed(x))

def powers(x):
    """yield powers of x, starting from x**0 forever"""
    power = 1
    while True:
        yield power
        power *= x

def delnan():
    # in Python 2, use itertools.izip!
    return sum(int(place) * place_weight for place_weight, place in
               itertools.izip(powers(2), reversed(x)))

def emil():
    return sum([int(y[1])*2**y[0] for y in enumerate(x)])

def steve():
    y = 0
    for i,j in enumerate(x):
        if j: y += int(j)<<i
    return y

if __name__ == '__main__':
    names = ['sven1', 'sven2', 'liori', 'delnan', 'emil', 'steve']
    for name in names:
        print "%10s: %2.5f" % (name, timeit.timeit( 'test.%s()' % name, 'import test', number=1000))