Python实现分割文件及合并文件的方法

本文实例讲述了Python实现分割文件及合并文件的方法。分享给大家供大家参考。具体如下：

分割文件split.py如下：

    #!/usr/bin/python
    ##########################################################################
    # split a file into a set of parts; join.py puts them back together;
    # this is a customizable version of the standard unix split command-line 
    # utility; because it is written in Python, it also works on Windows and
    # can be easily modified; because it exports a function, its logic can 
    # also be imported and reused in other applications;
    ##########################################################################
    import sys, os
    kilobytes = 1024
    megabytes = kilobytes * 1000
    chunksize = int(1.4 * megabytes)     # default: roughly a floppy
    def split(fromfile, todir, chunksize=chunksize): 
     if not os.path.exists(todir):     # caller handles errors
      os.mkdir(todir)       # make dir, read/write parts
     else:
      for fname in os.listdir(todir):   # delete any existing files
       os.remove(os.path.join(todir, fname)) 
     partnum = 0
     input = open(fromfile, 'rb')     # use binary mode on Windows
     while 1:          # eof=empty string from read
      chunk = input.read(chunksize)    # get next part <= chunksize
      if not chunk: break
      partnum = partnum+1
      filename = os.path.join(todir, ('part%04d' % partnum))
      fileobj = open(filename, 'wb')
      fileobj.write(chunk)
      fileobj.close()       # or simply open().write()
     input.close()
     assert partnum <= 9999       # join sort fails if 5 digits
     return partnum
    if __name__ == '__main__':
     if len(sys.argv) == 2 and sys.argv[1] == '-help':
      print 'Use: split.py [file-to-split target-dir [chunksize]]'
     else:
      if len(sys.argv) < 3:
       interactive = 1
       fromfile = raw_input('File to be split? ')  # input if clicked 
       todir = raw_input('Directory to store part files? ')
      else:
       interactive = 0
       fromfile, todir = sys.argv[1:3]     # args in cmdline
       if len(sys.argv) == 4: chunksize = int(sys.argv[3])
      absfrom, absto = map(os.path.abspath, [fromfile, todir])
      print 'Splitting', absfrom, 'to', absto, 'by', chunksize
      try:
       parts = split(fromfile, todir, chunksize)
      except:
       print 'Error during split:'
       print sys.exc_info()[0], sys.exc_info()[1]
      else:
       print 'Split finished:', parts, 'parts are in', absto
      if interactive: raw_input('Press Enter key') # pause if clicked

合并文件join_file.py如下：

    #!/usr/bin/python
    ##########################################################################
    # join all part files in a dir created by split.py, to recreate file. 
    # This is roughly like a 'cat fromdir/* > tofile' command on unix, but is 
    # more portable and configurable, and exports the join operation as a 
    # reusable function. Relies on sort order of file names: must be same 
    # length. Could extend split/join to popup Tkinter file selectors.
    ##########################################################################
    import os, sys
    readsize = 1024
    def join(fromdir, tofile):
     output = open(tofile, 'wb')
     parts = os.listdir(fromdir)
     parts.sort()
     for filename in parts:
      filepath = os.path.join(fromdir, filename)
      fileobj = open(filepath, 'rb')
      while 1:
       filebytes = fileobj.read(readsize)
       if not filebytes: break
       output.write(filebytes)
      fileobj.close()
     output.close()
    if __name__ == '__main__':
     if len(sys.argv) == 2 and sys.argv[1] == '-help':
      print 'Use: join.py [from-dir-name to-file-name]'
     else:
      if len(sys.argv) != 3:
       interactive = 1
       fromdir = raw_input('Directory containing part files? ')
       tofile = raw_input('Name of file to be recreated? ')
      else:
       interactive = 0
       fromdir, tofile = sys.argv[1:]
      absfrom, absto = map(os.path.abspath, [fromdir, tofile])
      print 'Joining', absfrom, 'to make', absto
      try:
       join(fromdir, tofile)
      except:
       print 'Error joining files:'
       print sys.exc_info()[0], sys.exc_info()[1]
      else:
       print 'Join complete: see', absto
      if interactive: raw_input('Press Enter key') # pause if clicked

希望本文所述对大家的Python程序设计有所帮助。