Este script permite que uma série de arquivos sejam organizados em vários DVDs/CDs de forma otimizada, isto é, tentando sempre utilizar ao máximo o espaço disponível na mídia. É útil quando você não quer pensar muito na melhor organização e eu venho usado para organizar os meus arquivos de backup. Ao final, ele lista uma opção de organização. Como o algoritmo é estatístico, você pode rodar novamente para ter um resultado diferente, apesar de construído com os mesmos critérios.

• Download dvdsplit.py
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Esconder código-fonte

"""
Este programa usa uma rede neural do tipo Hopfield para a solução do problema. Basicamente é necessário especificar o diretório onde os arquivos estão, o tamanho da mídia e a folga máxima. Se nenhum parâmetro é especificado, é usado o diretório corrente, uma mídia de 4500MB (DVD) e uma folga de 50MB. A folga diz o quanto o algoritmo pode encarar margem de erro, já que em geral não é possível ter uma divisão sempre perfeita.

Rode com dvdsplit.py -h para informações da linha de comando. É meu primeiro programa em Python, comentário são bem vindos. 
"""
"""
DVD Split, by Marcelo Barros (marcelobarrosalmeida(at)yahoo.com.br)
Sept/13/2005
$Id: dvdsplit.py,v 1.1 2005/09/13 14:54:36 barros Exp $
"""
import random
import math
import os
import sys
from optparse import OptionParser
import psyco

def currentSize(files, selected):
    """
    Calculate the size of the current selection.
    
    Parameters:
    - files: list with file sizes
    - selected: list with 1 or -1, indicating if the file was selected or not

    Returns:
    - the current selection size
    """
    sz = 0
    for i in range(len(files)):
        if(selected[i] > 0):
            sz = sz + files[i]
    return sz

def energyFun(files,selected,dvdsz):
    """
    Energy function used. In this case is:
    f(x) = |current_size - dvdsize |

    Parameters:
    - files: list with file sizes
    - selected: list with 1 or -1, indicating if the file was selected or not
    - dvdsz: dvd size

    Returns:
    - energy function value for the current selection
    """
    energ = 0
    for i in range(len(files)):
        if selected[i] > 0:
            energ = energ + files[i]
    energ = abs(energ - dvdsz)
    return energ

def dvdInitialGuess(files,selected,dvdsz):
    """
    Just provide an initial random guess to the algorithm

    Parameters:
    - files: list with file sizes
    - selected: list with 1 or -1, indicating if the file was selected or not
    - dvdsz: dvd size    
    """
    l = len(files)
    idx = range(l)
    idx = random.sample(idx,l)

    t = 0
    for i in range(l):
        j = idx[i]
        t = t + files[j]
        selected[j] = 1
        if t >= dvdsz:
            break

def dvdSplit(files,dvdsz,slack=50,itermax=3000,beta=0.005):
    """
    Given a list with file sizes, the dvd size and the acceptable slack
    this routine gives a subset that fits in one dvd.  

    Parameters:
    - files: list with file sizes
    - dvdsz: dvd size (single side)
    - slack: maximum acceptable error when calculating the selection
    - itermax: maximum number of iteration (default=2000)
    - beta: sigmoid parameter (default 0.005, empirically determined)

    Returns:
    - indexes of selected files: [ idx1, idx2, ..., idxn ]
    - indexes of not selected files: [ idx1, idx2, ..., idxn ]
    - current selection size
    - iteration used to calculate
    """
    running = True
    iter = 0
    numfiles = len(files)
    selected = [-1 for x in range(numfiles)]
    dvdInitialGuess(files,selected,dvdsz)

    sz = currentSize(files,selected) # maximum size must be greather than dvdsize

    if(sz > dvdsz):
        while(running and iter < itermax):
            # current energy 
            e1 = energyFun(files,selected,dvdsz)
            # change state for random node
            n = random.randint(0,numfiles-1)
            selected[n] = -selected[n]
            # new energy
            e2 = energyFun(files,selected,dvdsz)
            # evaluate the change against sigmoid and accept it or not
            # according to a uniform probability
            sig = (1/( 1 + math.exp(beta*(e2-e1))))
            if sig < random.uniform(0,1):
                selected[n] = -selected[n] # state not accepted
            sz = currentSize(files,selected)
            # testing exit condition: (dvdsz - slack) < currentSize < dvdsz
            if ( (sz >= (dvdsz - slack)) and (sz < dvdsz) ):
                running = False
            iter = iter + 1

    sel = []
    notsel = []
    for i in range(numfiles):
        if selected[i] > 0:
            sel.append(i)
        else:
            notsel.append(i)
    #print "Solution found in %d iterations. Compilation size is %d (%d files)" % (iter,sz,len(sel))
    return sel,notsel,sz,iter

def dvdsSplit(files,dvdsz,slack=50,itermax=3000,beta=0.005):
    """
    Given a list with file sizes, the dvd size and the acceptable slack
    this routine distributes the selection over several dvs.

    Parameters:
    - files: list with file sizes
    - dvdsz: dvd size (single side)
    - slack: maximum acceptable error when calculating the selection (default=50)
    - itermax: maximum number of iteration (default=2000)
    - beta: sigmoid parameter (default 0.005, empirically determined)

    Returns:
    - indexes of selected files per dvds:
      [ [idx1, idx2, ..., idxn], [idx1, idx2, ..., idxm], ..., [idx1, idx2, ..., idxk] ]
    - compilation sizes: [ size1, size2, ..., sizen ]      
    """
    # first create a dictionary with all file sizes indexed. Files choosen
    # by dvdSplit will be removed from this dictionary until it becomes empty
    filesdic = dict()
    n = len(files)
    for i in range(n):
        filesdic[i] = files[i]
    dvds = []
    sz = []
    running = True
    r = 1
    while(running):
        v = filesdic.values()
        k = filesdic.keys()
        print "Starting DVD %02d [%3.2f%% completed]" % (r,100-100*len(v)/n)
        maxtries = 50
        while(True):
            sel,ns,dsz,iter = dvdSplit(v,dvdsz,slack,itermax,beta)
            if dsz < dvdsz:
                break;
            maxtries = maxtries - 1
            if(maxtries == 0):
                print "Could not find a good solution for DVD %d in 50 attempts. Try again, please." % (r)
                sys.exit(1)
        # getting indexes
        r = r + 1
        d = []
        for s in sel:
            d.append(k[s])
            del filesdic[k[s]]
        # saving dvd compilation
        dvds.append(d)
        sz.append(dsz)
        if len(ns) == 0:
            running = False

    return dvds, sz

def dvdConsistency(filenames,filesizes,dvdsz):
    """
    Consistency checks.

    Parameters:
    - filenames: file names dict
    - filesizes: file sizes dict
    - dvds: dvd size
    """
    # look for any file bigger than dvd side
    for i in filesizes:
        if filesizes[i] >= dvdsz:
            print "Size %d is bigger than dvd size %d" % (filesizes[i],dvdsz)
            sys.exit(1)

def printDvdLayout(filesizes,filenames,dvdsz,dvds,s):
    """
    Print results
    """
    i = 0
    n = len(dvds)
    tts = []
    print "\nSummary:"
    for dvd in dvds:
        tt = []
        i = i + 1
        for track in dvd:
            tt.append(filesizes[track])
        tts.append(sum(tt))
        print "[DVD %d/%d, SIZE %dMBs, USAGE %2.2f%%]" % (i,n,tts[i-1],100.0*tts[i-1]/dvdsz)

    i = 0
    print "\nFile seletion per DVD:"
    for dvd in dvds:
        i = i + 1
        print "[DVD %d/%d, SIZE %dMBs]" % (i,n,tts[i-1])
        for track in dvd:
            files = filenames[track].split(',')
            files.sort()
            for f in files:
                print "\t%s" % (f)

def buildDvds(basedir,dvdsz,slack):
    """
    Get the files list and call optimization routines
    """
    filelist = os.listdir(basedir)
    filenames = dict()
    filesizes = dict()
    i = 0
    print "\nFiles at base directory %s (DVD size = %d, slack = %d)" % (basedir,dvdsz,slack)
    for f in filelist:
        filename = basedir+f
        if os.path.isfile(filename):
            filenames[i] = f
            # in MB, rounded up
            filesizes[i] = int(os.path.getsize(filename)/1024.0**2 + 1)
            print '[%5.2fMB ] %s' % (filesizes[i],filenames[i])
            i = i + 1

    print "\nChecking consistency ..."
    dvdConsistency(filenames,filesizes,dvdsz)
    dvds, s = dvdsSplit(filesizes.values(),dvdsz,slack)
    printDvdLayout(filesizes,filenames,dvdsz,dvds,s)

def main():

    usage = "Usage: %prog [options]"
    cmdline = OptionParser(usage)
    cmdline.add_option("-d", "--dir",  action="store", dest="basedir", type="string", default=".",    metavar="DIR",      help="Directory where files are stored")
    cmdline.add_option("-s", "--size", action="store", dest="dvdsz",   type="int",    default="4500", metavar="SIZE",     help="DVD size")
    cmdline.add_option("-l", "--slack",action="store", dest="slack",   type="int",    default="50",   metavar="SLACK",    help="Maximum acceptable error")

    (options, args) = cmdline.parse_args()

    if(os.path.isdir(options.basedir) == False):
        print "%s is not a valid directory" %(options.basedir)
        sys.exit(1)

    options.basedir.strip()
    basedir = os.path.normpath(options.basedir)
    if(os.path.isdir("c:\\")):
        basedir = basedir + "\\"
    else:
        basedir = basedir + "//"

    buildDvdsPrx = psyco.proxy(buildDvds)
    buildDvdsPrx(basedir,int(options.dvdsz),int(options.slack))

if __name__ == "__main__":

    main()

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