# based on Recipe 466302: Sorting big files the Python 2.4 way # by Nicolas Lehuen import os from tempfile import gettempdir from itertools import islice , cycle from collections import namedtuple import heapq Keyed = namedtuple ( "Keyed" , [ "key" , "obj" ]) def merge ( key = None , * iterables ): # based on code posted by Scott David Daniels in c.l.p. # http://groups.google.com/group/comp.lang.python/msg/484f01f1ea3c832d if key is None : keyed_iterables = iterables else : keyed_iterables = [( Keyed ( key ( obj ), obj ) for obj in iterable ) for iterable in iterables ] for element in heapq . merge ( * keyed_iterables ): yield element . obj def batch_sort ( input , output , key = None , buffer_size = 32000 , tempdirs = None ): if tempdirs is None : tempdirs = [] if not tempdirs : tempdirs . append ( gettempdir ()) chunks = [] try : with open ( input , 'rb' , 64 * 1024 ) as input_file : input_iterator = iter ( input_file ) for tempdir in cycle ( tempdirs ): current_chunk = list ( islice ( input_iterator , buffer_size )) if not current_chunk : break current_chunk . sort ( key = key ) output_chunk = open ( os . path . join ( tempdir , ' %06i ' % len ( chunks )), 'w+b' , 64 * 1024 ) chunks . append ( output_chunk ) output_chunk . writelines ( current_chunk ) output_chunk . flush () output_chunk . seek ( 0 ) with open ( output , 'wb' , 64 * 1024 ) as output_file : output_file . writelines ( merge ( key , * chunks )) finally : for chunk in chunks : try : chunk . close () os . remove ( chunk . name ) except Exception : pass if __name__ == '__main__' : import optparse parser = optparse . OptionParser () parser . add_option ( '-b' , '--buffer' , dest = 'buffer_size' , type = 'int' , default = 32000 , help = '''Size of the line buffer. The file to sort is divided into chunks of that many lines. Default : 32,000 lines.''' ) parser . add_option ( '-k' , '--key' , dest = 'key' , help = '''Python expression used to compute the key for each line, "lambda line:" is prepended.

Example : -k "line[5:10]". By default, the whole line is the key.''' ) parser . add_option ( '-t' , '--tempdir' , dest = 'tempdirs' , action = 'append' , default = [], help = '''Temporary directory to use. You might get performance improvements if the temporary directory is not on the same physical disk than the input and output directories. You can even try providing multiples directories on differents physical disks. Use multiple -t options to do that.''' ) parser . add_option ( '-p' , '--psyco' , dest = 'psyco' , action = 'store_true' , default = False , help = '''Use Psyco.''' ) options , args = parser . parse_args () if options . key : options . key = eval ( 'lambda line : ( %s )' % options . key ) if options . psyco : import psyco psyco . full () batch_sort ( args [ 0 ], args [ 1 ], options . key , options . buffer_size , options . tempdirs )