python数据类型之‘元组’

水深无声 2022-05-16 02:55 337阅读 0赞

## 1.元组的定义 ##

** 元组（tuple）:   ** 带了紧箍咒的列表;  
之所以这样称，是因为元组是不可变数据类型,没有增删改查;     但其可以存储任意数据类型;

**1.定义元组**

> **t = (1, 2.1, 2e+10, True, 2j+3, \[1,2,3\],(1,2,3) )  
> print(t, type(t))**

![70][]

如果元组里面包含可变数据类型， 可以间接修改元组内容;

> **t1 = (\[1,2,3\], 4)  
> t1\[0\].append(4)  
> print(t1)**

![70 1][]  
  
元组如果只有一个元素， 后面一定要加逗号, 否则数据类型不确定；

> **t2 = ()  
> t3 = tuple(\[\])  
> t4 = ('hello')  
> t5 = ('hello',)  
> print(type(t2), type(t3), type(t4), type(t5))**

![70 2][]

**2.元组的特性**

**1.重复（\*）**

> **allowUsers = ('root', 'westos', 'fentiao')**
> 
> **print（allowUsers\*3）**

**2.连接（+）**

> **allowUsers = ('root', 'westos', 'fentiao')**
> 
> **print(allowUsers + ('fensi', 'fendai'))**
> 
>

**3.成员操作符（in）**

> **allowUsers = ('root', 'westos', 'fentiao')**
> 
> **print('westos' in allowUsers)  
> print('westos' not in allowUsers)**

![70 3][]

**4.索引**

**5.切片**

**6.for循环**

> **allowUsers = ('root', 'westos', 'fentiao')  
> print("显示".center(50, '\*'))  
> for user in allowUsers:  
>     print("白名单用户:%s" %(user))**

> **\# \#** for循环并且求索引(枚举)
> 
> **allowUsers = ('root', 'westos', 'fentiao')**
> 
> **print("索引显示".center(50, '\*'))  
> for index,user in  enumerate(allowUsers):\#\#\#（枚举）  
>     print("第%d个白名单用户: %s" %(index+1, user))**

![70 4][]

**7.zip: 集和用户名和密码两个元组， 元素之间一一对应**

> **allowUsers = ('root', 'westos', 'fentiao')  
> allowPasswd = ('123', '456', '789')  
> for user, passwd in  zip(allowUsers, allowPasswd):  
>     print(user,':', passwd)**

![70 5][]

**3.元组的常用方法**

> **t = (1,2, 'a', 'c', 'a')  
> print(t.index('c'))     \#\#\#\#求某个字符的索引值  
> print(t.count('a'))     \#\#\#\#求某个字符出现的次数**
> 
> **print(len(t))     \#\#\#查看元组的长度，即元素个数**

**4.元组的应用场景**

1.  变量交换数值:

> **a = 1  
> b = 2**
> 
> **b,a = a,b  
> \# 1. 先把(a,b)封装成一个元组, (1,2)  
> \# 2. b,a = a,b ======> b,a =(1,2)  
> \# 3. b = (1,2)\[0\], a=(1,2)\[1\]  
> print(a,b)**

![70 6][]

2.打印变量值

> **name = 'westos'  
> age = 10  
> t = (name, age)  
> print("name: %s, age: %d" %(name, age))  
> print("name: %s, age: %d" %t)**

![70 7][]

3.元组的赋值:（有多少个元素， 就用多少个变量接收）

> **t = ('westos', 10, 100)  
> name, age,score  = t  
> print(name, age, score)**

![70 8][]

**5.练习**

游戏记分器

给出一组用元组表示的成绩，去掉最高分和最低分，求平均成绩

> **scores = (100, 89, 45, 78, 65)  
> \# 先对元组进行排序  
> \# scoresLi = list(scores)  
> \# scoresLi.sort()  
> \# print(scoresLi)    （可以先将元组转化为列表，再排序）**
> 
>   
> **scores = sorted(scores)  
> \# python3中，\*就像一个容器，容纳了中间的所有值  
> minScore, \*middleScore, maxScore = scores  
> print(minScore, middleScore, maxScore)  
> print("最终成绩为: %.2f" %(sum(middleScore)/len(middleScore)))**

![70 9][]

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