Ô­À´ÊÇÁ´±íÍƵ¼Ê½£¬¸ÐлBaoYongjun £¬Í¬Ê±Ò²¸ÐлÁõöÎ £¡
  ----- Original Message ----- 
  From: BaoYongjun
  To: python-chinese at lists.python.cn
  Sent: Saturday, May 07, 2005 3:58 PM
  Subject: Re: [python-chinese] ËüÈçºÎ¹¤×÷


  „¢ÀÚ£¬ÄúºÃ£¡

  ¡¡¡¡ÏÂÃæÕª×ÔPython ÊÖ²á(v2.3)   ÒëÕß: ÁõöÎ
  5.1.4 Á´±íÍƵ¼Ê½
  Á´±íÍƵ¼Ê½ÌṩÁËÒ»¸ö´´½¨Á´±íµÄ¼òµ¥Í¾¾¶£¬ÎÞÐèʹÓà map()£¬ filter() ÒÔ¼° 
lambda¡£·µ»ØÁ´±íµÄ¶¨Òåͨ³£Òª±È´´½¨ÕâЩÁ´±í¸üÇåÎú¡£Ã¿Ò»¸öÁ´±íÍƵ¼Ê½°üÀ¨ÔÚÒ»¸öforÓï¾äÖ®ºóµÄ±í´ïʽ£¬Áã»ò¶à¸öfor»òifÓï¾ä¡£·µ»ØÖµÊÇÓÉfor»òif×Ó¾äÖ®ºóµÄ±í´ïʽµÃµ½µÄÔªËØ×é³ÉµÄÁ´±í¡£Èç¹ûÏëÒªµÃµ½Ò»¸öÔª×飬±ØÐëÒª¼ÓÉÏÀ¨ºÅ¡£

>>> freshfruit = ['  banana', '  loganberry ', 'passion fruit  ']
>>> [weapon.strip() for weapon in freshfruit]
['banana', 'loganberry', 'passion fruit']
>>> vec = [2, 4, 6]
>>> [3*x for x in vec]
[6, 12, 18]
>>> [3*x for x in vec if x > 3]
[12, 18]
>>> [3*x for x in vec if x < 2]
[]
>>> [[x,x**2] for x in vec]
[[2, 4], [4, 16], [6, 36]]
>>> [x, x**2 for x in vec]      # error - parens required for tuples
  File "", line 1, in ?
    [x, x**2 for x in vec]
               ^
SyntaxError: invalid syntax
>>> [(x, x**2) for x in vec]
[(2, 4), (4, 16), (6, 36)]
>>> vec1 = [2, 4, 6]
>>> vec2 = [4, 3, -9]
>>> [x*y for x in vec1 for y in vec2]
[8, 6, -18, 16, 12, -36, 24, 18, -54]
>>> [x+y for x in vec1 for y in vec2]
[6, 5, -7, 8, 7, -5, 10, 9, -3]
>>> [vec1[i]*vec2[i] for i in range(len(vec1))]
[8, 12, -54]ΪʹÁ´±íÍƵ¼Ê½Æ¥ÅäforÑ­»·µÄÐÐΪ£¬¿ÉÒÔÔÚÍƵ¼Ö®Íâ±£ÁôÑ­»·±äÁ¿£º

>>> x = 100                     # this gets overwritten
>>> [x**3 for x in range(5)]
[0, 1, 8, 27, 64]
>>> x                           # the final value for range(5)
4
  ======== 2005-05-07 14:12:00 ÄúÔÚÀ´ÐÅÖÐдµÀ£º ========

          ÔÚÔĶÁ¡¶¼òÃ÷PythonÖ¸ÄÏ¡·µÄ[Áбí×ÛºÏ]²¿·ÖÓöµ½Ò»¶Î³ÌÐò´úÂ룬ÈçÏ£º
          listone = [2, 3, 4]
          listtwo = [2*i for i in listone if i > 2]
          print listtwo

          Êä³öÈçÏ£º
          [4, 6, 8]

          ²»Ã÷°×2*i for i in listone if i > 2ÊÇÈçºÎ¹¤×÷µÄ£¬Çë¸÷λָ½Ì£¬²»Ê¤¸Ð¼¤£¡

          ******************************
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           „¢ÀÚ<liul at dhc.com.cn>
           tel:+86-411-8474-6465
           FAX£º+86-411-8474-6500
           ******************************

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  ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡BaoYongjun
  ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡byj at net.pku.edu.cn
  ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡2005-05-07



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