Diff for "ObpLovelyPython/PCS205" - Woodpecker Wiki for CPUG

Differences between revisions 2 and 3

status

草稿

清风; 100%

enumerate

小白:Python中的循环,想知道现在循环了几次好麻烦,总要在循环外定义一个变量,然后每次循环再加1,像这样:

i=0
for obj in objlist:
    i+=1
    print i

行者:..........请尝试enumerate

   1 mylist=["a","b","c"]
   2 for index,obj in enumerate(mylist):
   3     print index,obj

0,"a"
1,"b"
2,"c"

行者:以一个小例子,展示map的威力,将数组中每一个数乘以2

   1 map(lambda x:x*2,[1,2,3,4,5])

行者:同时循环两个一样长的数组

   1 for x,y in zip([1,2,3],[4,5,6]):
   2     print "x,y",x,y

行者:过滤掉,数组中小于3的数

   1 filter(lambda x:x>3,[1,2,3,4,5])

-  ⇤ ← Revision 2 as of 2008-06-17 12:59:10 → 
  Size: 585
  Editor: qingfeng
  Comment:
+   ← Revision 3 as of 2008-06-24 07:38:20 → ⇥
  Size: 1077
  Editor: qingfeng
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 29:
+== 其他内置函数 ==
 * 小白:enumerate很方便,那Python还有什么内置函数吗?
 * 行者:map,zip,filter,等等,很多.

=== map ===
行者:以一个小例子,展示map的威力,将数组中每一个数乘以2
{{{#!python
map(lambda x:x*2,[1,2,3,4,5])
}}}
行者:同时循环两个一样长的数组
{{{#!python
for x,y in zip([1,2,3],[4,5,6]):
    print "x,y",x,y
}}}
行者:过滤掉,数组中小于3的数
{{{#!python
filter(lambda x:x>3,[1,2,3,4,5])
}}}