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python常用内置函数1

时间:2018-03-19 22:43:34      阅读:243      评论:0      收藏:0      [点我收藏+]

标签:value   运算   for   ghost   cal   min   ==   lis   类型   

1,abs 求绝对值

>>> abs( -1 )
1
>>> abs( 1 )
1
>>> 

2,max, min求序列最大值与最小值

>>> l = [ 1, 10, -6, 2, 100 ]
>>> max( l )
100
>>> min( l )
-6

3,len求列表的长度

>>> s = ghostwu
>>> len( s )
7
>>> l = [ 10, 20, 30 ]
>>> len( l )
3
>>> t = ( 10, 20 )
>>> len( t )
2
>>> dic = { a : 10, b : 20, c : -1, d : 100 }
>>> len( dic )
4

4,divmod求商和余数

>>> divmod( 1, 2 )
(0, 1)
>>> divmod( 2, 1 )
(2, 0)
>>> 

5,pow,两个值,幂运算,3个值,先幂运算,再除以第三个值,求余数

>>> pow( 3, 4 )
81

>>> pow( 2, 2, 6 )
4
>>> 

6,callable测试函数是否可以被调用

>>> callable( min )
True
>>> callable( f )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name f is not defined
>>> callable( abs )
True
>>> def f():
...     pass
... 
>>> callable( f )
True

7,类型判断

>>> l = [ 10, 20 ]
>>> type( l )
<type list>
>>> type( [] )
<type list>
>>> if( type( [] ) == type( l ) ):
...     print yes
... 
yes
>>> t = ( 10, 20 )
>>> if( type( [] ) == type ( t ) ):
...     print yes
... else:
...     print no
... 
no
>>> 

也可以用isinstance判断 

>>> l = [ 10, 20 ]
>>> isinstance( l, list )
True
>>> type( () )
<type tuple>
>>> isinstance( ( 10, 20 ), tuple )
True
>>> isinstance( l, tuple )
False
>>> 

8,cmp比较字符串大小

>>> cmp( a, b )
-1
>>> cmp( b, ac )
1
>>> cmp( a, ab )
-1
>>> cmp( a, a )
0
>>> 

9,range与类型转换等

>>> range( 1, 10 )
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> range( -1, -10, -1 )
[-1, -2, -3, -4, -5, -6, -7, -8, -9]
>>> range( 1, 10, 5 )
[1, 6]
>>> 
>>> s = ghostwu
>>> type( s )
<type str>
>>> int( s )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: ghostwu
>>> s = 20
>>> type( s )
<type str>
>>> int( s )
20
>>> type( s )
<type str>
>>> s + abc
20abc
>>> int( s ) + abc
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: int and str
>>> int( s ) + 10
30
>>> 

字符串为数值类型的才能转成整形

当然还有其他类型转换等

 

python常用内置函数1

标签:value   运算   for   ghost   cal   min   ==   lis   类型   

原文地址:https://www.cnblogs.com/ghostwu/p/8605421.html

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