012 元组

简介

• 英文名：tuple
• 可以看成不可更改的 list

创建

• 提示：逗号比括号要关键！

例1

>>> t1 = ()
>>> t2 = (1,)
>>> t3 = 1,
>>> t4 = (1)
>>> 
>>> type(t1)
<class 'tuple'>
>>> type(t2)
<class 'tuple'>
>>> type(t3)
<class 'tuple'>
>>> type(t4)
<class 'int'>
>>> 

例2

>>> t1 = (1, 2, 3)
>>> t2 = ([1, 2, 3])
>>> t3 = tuple([1, 2, 3])
>>> 
>>> type(t1)
<class 'tuple'>
>>> type(t2)
<class 'list'>
>>> type(t3)
<class 'tuple'>
>>> 

例3

>>> t = tuple(1)
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    t = tuple(1)
TypeError: 'int' object is not iterable
>>> 

特性

概述

• 元组是序列表，有序
• 元组数据值相当于“只读”模式，即，可以访问但不能修改
• 元组数据值可以是任意类型
• 与 list 仅一个区别：不可修改
• 可以索引、分片、序列间计算、成员资格操作等

索引

>>> t = (1, 2, 3)
>>> t[0]
1
>>> t[-1]
3
>>> t[5]
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    t[5]
IndexError: tuple index out of range
>>> 

分片

>>> t1 = (1, 2, 3, 4, 5)
>>> t2 = t1[::2]
>>> t1
(1, 2, 3, 4, 5)
>>> t2
(1, 3, 5)
>>> 
>>> t1[3:10]
(4, 5)
>>> 

序列运算

>>> t1 = (1, 2, 3)
>>> t2 = (4, 5, 6)
>>> id(t1)
2284419977472
>>> t1 = t1 + t2
>>> t1
(1, 2, 3, 4, 5, 6)
>>> id(t1)
2284420072640
>>> 
>>> t2 * 3
(4, 5, 6, 4, 5, 6, 4, 5, 6)
>>> 

成员检测

>>> t = (1, 2, 3)
>>> 1 in t
True
>>> 

遍历

例1

>>> t1 = (1, 2, 3, "york", "fish")
>>> for i in t1:
    print(i, end=' ')

    
1 2 3 york fish 
>>> 
>>> t2 = ((1, 2, 3), (4, 5, 6), ("york", "fish"))
>>> for i in t2:
    print(i, end=' ')

    
(1, 2, 3) (4, 5, 6) ('york', 'fish') 
>>> 

例2

>>> t = ((1, 2, 3), (4, 5, 6), (7, 8, 9))
>>> for i, j, k in t:
    print(i, j, k)

    
1 2 3
4 5 6
7 8 9
>>> 

内置方法

查看

• dir(tuple): 列出 tuple 的方法
• help(tuple): 查看开发者对 tuple 方法所编写的详细描述文档
  • help(tuple.count) 可以仅查看 count() 的用法

count()

• 与字符串、列表中的用法类似
• 计算指定数据在元组中出现的次数

>>> t = (1, 2, 3, 3, 3, 4, 5, 6)
>>> t.count(3)
3
>>> 

index()

• 与字符串、列表中的用法类似
• 索引指定元素在元组中的位置

>>> t = (1, 2, 3, 3, 3, 4, 5, 6)
>>> t.index(3)
2
>>> t.index(3, 4)
4
>>> t.index(10)
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    t.index(10)
ValueError: tuple.index(x): x not in tuple
>>> 

别的方法

len()

>>> t = (1, 2, 3)
>>> len(t)
3
>>> 

max() & min()

>>> t = (1, 3, 5, 6, 4, 2)
>>> max(t)
6
>>> min(t)
1
>>> 

del

>>> t = (1, 2, 3)
>>> del t
>>> t
Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
    t
NameError: name 't' is not defined
>>> 

• 写成 del(t) 也行

注意事项

例1 “第二层”

>>> t = (1, [2, 3, 4], 5)
>>> t[1][0] = 22
>>> t
(1, [22, 3, 4], 5)
>>> 

例2

>>> t1 = ("Amy Green", "Johnny Lee", "Tony black")
>>> t1 = t1[:2] + ("York Fish",) + t1[2:]  # t[2:] 不能偷懒写成 t[-1]
>>> t1
('Amy Green', 'Johnny Lee', 'York Fish', 'Tony black')
>>> 
>>> t2 = ("Amy Green", "Johnny Lee", "Tony black")
>>> t2 = t2[:2] + ("York Fish",) + t2[-1]
Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    t2 = t2[:2] + ("York Fish",) + t2[-1]
TypeError: can only concatenate tuple (not "str") to tuple
>>> 

例3

>>> t = ('Amy Green', 'Johnny Lee', 'York Fish', 'Tony black')
>>> t = t[:2] + t[3:]
>>> t
('Amy Green', 'Johnny Lee', 'Tony black')
>>>