python获取一组汉字拼音首字母的方法

#!/usr/bin/env python 
# -*- coding: utf-8 -*- 
def multi_get_letter(str_input): 
  if isinstance(str_input,unicode): 
    unicode_str = str_input 
  else: 
    try: 
      unicode_str = str_input.decode('utf8') 
    except: 
      try: 
        unicode_str = str_input.decode('gbk') 
      except: 
        print 'unknown coding' 
        return 
  return_list = [] 
  for one_unicode in unicode_str: 
    return_list.append(single_get_first(one_unicode)) 
  return return_list 
def single_get_first(unicode1): 
  str1 = unicode1.encode('gbk') 
  try:     
    ord(str1) 
    return str1 
  except: 
    asc = ord(str1[0]) * 256 + ord(str1[1]) - 65536 
    if asc >= -20319 and asc <= -20284: 
      return 'a' 
    if asc >= -20283 and asc <= -19776: 
      return 'b' 
    if asc >= -19775 and asc <= -19219: 
      return 'c' 
    if asc >= -19218 and asc <= -18711: 
      return 'd' 
    if asc >= -18710 and asc <= -18527: 
      return 'e' 
    if asc >= -18526 and asc <= -18240: 
      return 'f' 
    if asc >= -18239 and asc <= -17923: 
      return 'g' 
    if asc >= -17922 and asc <= -17418: 
      return 'h' 
    if asc >= -17417 and asc <= -16475: 
      return 'j' 
    if asc >= -16474 and asc <= -16213: 
      return 'k' 
    if asc >= -16212 and asc <= -15641: 
      return 'l' 
    if asc >= -15640 and asc <= -15166: 
      return 'm' 
    if asc >= -15165 and asc <= -14923: 
      return 'n' 
    if asc >= -14922 and asc <= -14915: 
      return 'o' 
    if asc >= -14914 and asc <= -14631: 
      return 'p' 
    if asc >= -14630 and asc <= -14150: 
      return 'q' 
    if asc >= -14149 and asc <= -14091: 
      return 'r' 
    if asc >= -14090 and asc <= -13119: 
      return 's' 
    if asc >= -13118 and asc <= -12839: 
      return 't' 
    if asc >= -12838 and asc <= -12557: 
      return 'w' 
    if asc >= -12556 and asc <= -11848: 
      return 'x' 
    if asc >= -11847 and asc <= -11056: 
      return 'y' 
    if asc >= -11055 and asc <= -10247: 
      return 'z' 
    return '' 
def main(str_input): 
  a = multi_get_letter(str_input) 
  b = '' 
  for i in a: 
    b= b+i 
  print b 
if __name__ == "__main__": 
  str_input=u'欢迎你' 
  main(str_input)