Extract every nth file

nthfile.py

import sys
import os
import shutil

if __name__ == "__main__":
	if len(sys.argv) < 4:
		print ("Usage: {} src_folder dst_folder ith_frame".format(sys.argv[0]))
		exit(0)
	
	ithFrame = int(sys.argv[3])

	if not os.path.exists(sys.argv[2]):
		os.makedirs(sys.argv[2])

	li = list(os.listdir(sys.argv[1]))
	li.sort()
	for fina in li[::ithFrame]:
		shutil.copyfile(os.path.join(sys.argv[1], fina), os.path.join(sys.argv[2], fina))