import random

def split(full_list,shuffle=False,ratio=0.2):
  n_total = len(full_list)
  offset = int(n_total * ratio)
  if n_total==0 or offset<1:
    return [],full_list
  if shuffle:
    random.shuffle(full_list)
  sublist_1 = full_list[:offset]
  sublist_2 = full_list[offset:]
  return sublist_1,sublist_2


if __name__ == "__main__":
  li = range(5)
  sublist_1,sublist_2 = split(li,shuffle=True,ratio=0.2)

  print sublist_1,len(sublist_1)
  print sublist_2,len(sublist_2)