text: #!/usr/bin/env python
  #
  # Subsample a set of PCD files from a source directory based on a given 
  # sampling rate. 
  #
  import re
  import os
  import sys
  import shutil
  
  if len(sys.argv) != 4:
      print "Usage: generate_subsample source_dir dest_dir sampling_rate"
      sys.exit()
  
  src_dir = sys.argv[1]
  dst_dir = sys.argv[2]
  sampling_rate = int(sys.argv[3])
  
  # Create the destination directory
  print 'Creating destination directory ...', 
  shutil.copytree(src_dir, dst_dir)
  print 'done'
  
  # Prune the destination directory
  print 'Pruning destination directory ...',
  for path, dirs, files in os.walk(dst_dir):
      if len(files):
          for f in files:
              m = re.search('(\d+_(\d+)).pcd', f)
              i = int(m.group(2))
              file = os.path.abspath(os.path.join(path, f))
              if i != 1 and ((i - 1) % sampling_rate) != 0: 
                  os.remove(file)
              else:
                  dir = os.path.abspath(os.path.join(path, m.group(1)))
                  os.mkdir(dir)
                  shutil.move(file, dir)
  print 'done'
  