Generates Multifractal data

multifract.py

#!/usr/bin/env python
#-*- coding: utf-8 -*-
# Copyright 2013 Subhodeep Moitra, all rights reserved
# subhodeep.moitra@gmail.com

import argparse
import os,sys

def log(n,base) :
    return 0 if n==1 else 1+log(n/base,base)

def get_trace(args) :
    """ Returns trace """
    base = len(args.biases)
    depth = log(args.ticks[0],base)

    if args.biases[0] > args.biases[1] :
        args.biases.reverse()

    probs = [b/100. for b in args.biases]

    def cdf_sub(i,arr):
        """ Convert pdf to cdf """
        if i < 0 : return 0
        arr[i] += cdf_sub(i-1,arr)
        return arr[i]

    convert_to_cdf = lambda arr : cdf_sub(len(arr)-1,arr)

    convert_to_cdf(probs)

    import random

    def sample(pos,level):
        """ Recurse levels and get a pos"""
        if level == 0 : return pos
        usample = random.random()
        #binIdx = [ prob < usample for prob in  probs].index(True)
        binIdx = next((idx for idx,prob in enumerate(probs)
                       if usample<prob),None)
        return sample(base*pos+binIdx,level-1)

    return [sample(0,depth) for _ in range(args.accesses[0])]


if __name__ == '__main__' :
    parser =  argparse.ArgumentParser(description="Generate multifract code")
    parser.add_argument('--biases',dest='biases',nargs='+',type=float,
                        help='The biases',default=[80,20])
    parser.add_argument('--ticks',dest='ticks',nargs=1,type=int,
                        help="Number of time ticks",default=[2048])
    parser.add_argument('--disk-accesses',dest='accesses',nargs=1,type=int,
                        help="Number of Disc Accesses",default=[2048])


    args = parser.parse_args()

    trace = get_trace(args)

    try :
        fout = open('trace.dat','w')
        for val in trace :
            print >>fout, val
    finally:
        fout.close()