Python起步——元组

元组和列表一样，也是一种序列，唯一的不同是元组不能修改。

1. 创建元组（tuple）

>>> t = ()       
>>> type(t)      
<class 'tuple'>  
>>> t = (1)      
>>> type(t)      
<class 'int'>    
>>> t = (1, )    
>>> type(t)      
<class 'tuple'>  
>>> t = 1,2,3    
>>> type(t)      
<class 'tuple'>  
>>> t = (1,2,3)  
>>> type(t)      
<class 'tuple'>  
>>> t = 1,
>>> type(t)
<class 'tuple'>

2. 元组分片

>>> t = (1,3,4,5,7,6)
>>> t1 = t[1::2]
>>> t1
(3, 5, 6)
>>> id(t)
1669982570824
>>> id(t1)
1669982801208

3. 元组相加

>>> t1 = (1,3,4)
>>> t2 = (5,6,7)
>>> t = t1 + t2
>>> t
(1, 3, 4, 5, 6, 7)

4. 元组相乘

>>> t1 = (1,3,4)
>>> t = t1 * 3
>>> t
(1, 3, 4, 1, 3, 4, 1, 3, 4)

5. 元组函数

基本跟list通用

>>> t = (1,2,3,5,6,7)
>>> len(t)
6
>>> max(t)
7
>>> min(t)
1
>>> l = [1,3,4,5,6]
>>> t = tuple(l)
>>> type(l)
<class 'list'>
>>> type(t)
<class 'tuple'>
>>> t.count(1)
1
>>> t.index(4)
2
>>> t.index(5)
3

5. 元组变量交换法

• 两个变量交换值

# 方法1
>>> a = 1
>>> b = 3
>>> c = a
>>> a = b
>>> b = c
>>> a
3
>>> b
1
# 方法2
>>> a, b = b, a
>>> a
1
>>> b
3