Python基础-列表_元组_字典_集合

本节内容

列表、元组操作

字符串操作

字典操作

集合操作

文件操作

字符编码与转码

1. 列表、元组操作

列表是我们最以后最常用的数据类型之一，通过列表可以对数据实现最方便的存储、修改等操作

定义列表示例

names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]

通过下标访问列表中的元素，下标从0开始计数

>>> names[0]
'ZhangYang'

切片示例1

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: huzhihua

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]

print(names)
print(names[0],names[2])
print(names[1:3])       #这就是切片（从0开始切，0就是ZhangYang）

执行结果：

['ZhangYang', ' Guyun', ' Xiangpeng', ' XuLiangChen']
ZhangYang  Xiangpeng
[' Guyun', ' Xiangpeng']

切片示例2

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]

print(names)
print(names[0],names[2])
print(names[1:3])  #这就是切片（从0开始，取下标1至下标3之间的数字，包括1，不包括3）
print(names[3])    #取第3个值，从0从始取
print(names[-2])   #在不知道是多长的情况下，取出最后2个位置
print(names[-2:])  #要取最后面的值，把-1省略掉
print(names[0:3])  #取从0-3
print(names[:3])   #如果是从头开始取，0可以忽略，跟上句效果一样

执行结果：

['ZhangYang', ' Guyun', ' Xiangpeng', ' XuLiangChen']
ZhangYang  Xiangpeng
[' Guyun', ' Xiangpeng']
XuLiangChen
Xiangpeng
[' Xiangpeng', ' XuLiangChen']
['ZhangYang', ' Guyun', ' Xiangpeng']
['ZhangYang', ' Guyun', ' Xiangpeng']

追加示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")   #追加到最后一行
print(names)

执行结果：

['ZhangYang', ' Guyun', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']

插入示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")   #追加到最后一行
names.insert(1,"nulige")     #插到那个位置 就写那个位置
names.insert(3,"Xinzhiyu")   #插入3的位置，不能批量插入
print(names)

执行结果：

['ZhangYang', 'nulige', ' Guyun', 'Xinzhiyu'' Xiangpeng', ' XuLiangChen', 'LeiHaidong']

修改示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")   #追加到最后一行
names.insert(1,"nulige")     #插到那个位置 就写那个位置
names.insert(3,"Xinzhiyu")   #插入3的位置，不能批量插入
names[2] ="XieDi" 　　　　　　 #修改
print(names)

执行结果：

['ZhangYang', 'nulige', 'XieDi', 'Xinzhiyu', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']

删除示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")   #追加到最后一行
names.insert(1,"Nulige")     #插到那个位置 就写那个位置
names.insert(3,"Xinzhiyu")   #插入3的位置，不能批量插入
names[2] ="XieDi"

#delete
names.remove("Nulige")   #删除Nulige
del names[1]
print(names)

执行效果：

删除前效果：

['ZhangYang', 'Nulige', 'XieDi', 'Xinzhiyu', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']

删除后效果：

['ZhangYang', 'Xinzhiyu', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']

index示例
查找XieDi的位置，并将找到的结果打印出来

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen"
names = ["ZhangYang"," Guyun","XieDi"," Xiangpeng"," XuLiangChen"]

# 查找XieDi的位置，并将找到的结果打印出来
print(names)
print(names.index("XieDi"))           #找到XieDi
print(names[names.index("XieDi")])    #把他打印出来

执行结果：

['ZhangYang', ' Guyun', 'XieDi', ' Xiangpeng', ' XuLiangChen']
2
XieDi

拷贝示例1

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = ["4ZhangYang"," #!Guyun","xXieDi"," Xiangpeng"," XuLiangChen"]
names2 = names.copy()
print(names)
print(names2)

执行结果:

['4ZhangYang', ' #!Guyun', 'xXieDi', ' Xiangpeng', ' XuLiangChen']
['4ZhangYang', ' #!Guyun', 'xXieDi', ' Xiangpeng', ' XuLiangChen']

拷贝示例2

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = ["4ZhangYang","#!Guyun","XiangPeng","ChenRonghua"]
names2 = names.copy()
print(names)
print(names2)
names[2] = "向鹏"
print(names)

执行结果：

['4ZhangYang', '#!Guyun', 'XiangPeng', 'ChenRonghua']
['4ZhangYang', '#!Guyun', 'XiangPeng', 'ChenRonghua']
['4ZhangYang', '#!Guyun', '向鹏', 'ChenRonghua']

拷贝示例3

1、浅拷贝

示例1

浅拷贝就是浅浅的copy一层

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige
#import copy
names = ["4ZhangYang","#!Guyun","XiangPeng",["alex","jack"],"ChenRonghua"]
names2 = names.copy()
print(names)
print(names2)
names[2] = "向鹏"
names[3][0] = "ALEXANDER"    #注意：复制列表，只会复制一层
print(names)
print(names2)

执行结果:

['4ZhangYang', '#!Guyun', 'XiangPeng', ['alex', 'jack'], 'ChenRonghua']
['4ZhangYang', '#!Guyun', 'XiangPeng', ['alex', 'jack'], 'ChenRonghua']
['4ZhangYang', '#!Guyun', '向鹏', ['ALEXANDER', 'jack'], 'ChenRonghua']
['4ZhangYang', '#!Guyun', 'XiangPeng', ['ALEXANDER', 'jack'], 'ChenRonghua']   #只拷贝了第一层，所以向鹏没有变

示例2

[b]运行结果报错，后期再解决[/b]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

import copy

person=['name',['a',100]]
#p1=copy.deepcopy(person)
p1=copy.copy(person)
p2=person[:]
p3=list(person)

结果省略...

示例3

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

person = ['name',['saving',100]]
p1=person[:]
p2=person[:]
p1[0]='alex'
p2[0]='fenjie'
p1[1][1]=50    #浅拷贝的作用，用于创建联合账号（100元，两人的两个账号各分一半，变成两个50元）
print(p1)
print(p2)

执行结果:

['alex', ['saving', 50]]
['fenjie', ['saving', 50]]

2、深拷贝

此实验还有点小问题，后期修改。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

import copy

names = ["4ZhangYang","#!Guyun","XiangPeng",["alex","jack"],"ChenRonghua"]
#names2 = names.copy()
#names2 = copy.copy(names)
names2 = copy.deepcopy(names)
print(names)
print(names2)
names[2] = "向鹏"
names[3][0] = "ALEXANDER"    #注意：复制列表，只会复制一层
print(names)
print(names2)

执行结果：省略......

列表循环

用for实现列表循环

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

#定义一个列表
names = ["4ZhangYang","#!Guyun","XiangPeng",["alex","jack"],"ChenRonghua"]
for i in names:
print(i)

执行结果：

4ZhangYang
#!Guyun
XiangPeng
['alex', 'jack']
ChenRonghua

跳着切片示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

#跳着切片
names = ["4ZhangYang","#!Guyun","XiangPeng",["alex","jack"],"ChenRonghua","Xuliangche"]
print(names[0:-1:2])
print(names[::2])
print(names[:])   #0到-1

for i in names:
print(i)

执行结果:

['4ZhangYang', 'XiangPeng', 'ChenRonghua']
['4ZhangYang', 'XiangPeng', 'ChenRonghua']
['4ZhangYang', '#!Guyun', 'XiangPeng', ['alex', 'jack'], 'ChenRonghua', 'Xuliangche']
4ZhangYang
#!Guyun
XiangPeng
['alex', 'jack']
ChenRonghua
Xuliangche

元组 (也叫不可变列表)

元组其实跟列表差不多，也是存一组数，只不是它一旦创建，便不能再修改，所以又叫只读列表。

语法

names = ("ales","jack","eric")

它只有两个方法，一个是count,一个是index。

示例：

#定义一个元组
tuple1 = (1, 2, '3', 4, '5')
# 定义了一个元组之后就无法再添加或修改元组中的元素
print tuple1[0]    # 元组的元素都有确定的顺序。元组的索引也是以0为基点的
print tuple1[-1]   # 负的索引从元组的尾部开始计数
print tuple1[1:3]  # 元组也可以进行切片操作。对元组切片可以得到新的元组。
# 可以使用 in 运算符检查某元素是否存在于元组中。
print 1 in tuple1   # True
#使用for in 进行遍历元组
for item in tuple1:
print item
# 如果需要获取item的序号 可以使用下面的遍历方法：
for index in range(len(tuple1)):
print tuple1[index]
# 还可以使用内置的enumerate函数
for index, item in enumerate(tuple1):
print '%i, %s' % (index, item)

统计示例

#统计有两个XieDi

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen "
names = ["ZhangYang"," Guyun","XieDi"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")
names.insert(1,"ChenRonghua")
names.insert(3,"Xinzhiyu")   #插入
names[2] ="XieDi"            #修改
print(names)
print(names.count("XieDi"))

执行结果：

['ZhangYang', 'ChenRonghua', 'XieDi', 'Xinzhiyu', 'XieDi', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']
2

清除示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen "
names = ["ZhangYang"," Guyun","XieDi"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")
names.insert(1,"ChenRonghua")
names.insert(3,"Xinzhiyu")   #插入
names[2] ="XieDi"            #修改
print(names)
print(names.count("XieDi"))

#clear
names.clear()
print(names)

执行结果

['ZhangYang', 'ChenRonghua', 'XieDi', 'Xinzhiyu', 'XieDi', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']
2
[]   

反转示例1

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = "ZhangYang Guyun Xiangpeng XuLiangChen "
names = ["ZhangYang"," Guyun","XieDi"," Xiangpeng"," XuLiangChen"]
names.append("LeiHaidong")
names.insert(1,"ChenRonghua")
names.insert(3,"Xinzhiyu")   #插入
names[2] ="XieDi"            #修改
print(names)
print(names.count("XieDi"))

#reverse
names.reverse()
print(names)

执行结果：

['ZhangYang', 'ChenRonghua', 'XieDi', 'Xinzhiyu', 'XieDi', ' Xiangpeng', ' XuLiangChen', 'LeiHaidong']
2
['LeiHaidong', ' XuLiangChen', ' Xiangpeng', 'XieDi', 'Xinzhiyu', 'XieDi', 'ChenRonghua', 'ZhangYang']    #对比第一行，反转过来了

反转示例2

>>> names
['Alex', 'Tenglan', 'Amy', 'Tom', 'Amy', 1, 2, 3]
>>> names.sort() #排序
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unorderable types: int() < str()   #3.0里不同数据类型不能放在一起排序了，擦
>>> names[-3] = '1'
>>> names[-2] = '2'
>>> names[-1] = '3'
>>> names
['Alex', 'Amy', 'Amy', 'Tenglan', 'Tom', '1', '2', '3']
>>> names.sort()
>>> names
['1', '2', '3', 'Alex', 'Amy', 'Amy', 'Tenglan', 'Tom']

排序示例

按ASCII码顺序进行排序的

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = ["4ZhangYang"," #!Guyun","xXieDi"," Xiangpeng"," XuLiangChen"]
print(names)

#排序(sort)
names.sort()
print(names)

执行结果：

['4ZhangYang', ' #!Guyun', 'xXieDi', ' Xiangpeng', ' XuLiangChen']
[' #!Guyun', ' Xiangpeng', ' XuLiangChen', '4ZhangYang', 'xXieDi']

扩展示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = ["4ZhangYang"," #!Guyun","xXieDi"," Xiangpeng"," XuLiangChen"]
print(names)

names2 = [1,2,3,4]
names.extend(names2)
print(names)

执行结果：

['4ZhangYang', ' #!Guyun', 'xXieDi', ' Xiangpeng', ' XuLiangChen']
['4ZhangYang', ' #!Guyun', 'xXieDi', ' Xiangpeng', ' XuLiangChen', 1, 2, 3, 4]

删除列表中的变量示例

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

names = ["4ZhangYang"," #!Guyun","xXieDi"," Xiangpeng"," XuLiangChen"]
print(names)

names2 = [1,2,3,4]
names.extend(names2)
del names2
print(names,names2)

执行结果：

会报错，因为找不到nemes2变量的值

Traceback (most recent call last):
['4ZhangYang', ' #!Guyun', 'xXieDi', ' Xiangpeng', ' XuLiangChen']
File "D:/python/day2/name_test02.py", line 11, in <module>
print(names,names2)
NameError: name 'names2' is not defined

字符串操作

>>> a = 'alex'
>>> a [1]
'l'
>>> a[2]
'e'

#备注：列表不能直接赋值

>>> a[2] = '222'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'str' object does not support item assignment

集合操作

集合的元素是不允许重复且无序的集合，集合就像是字典舍弃了值一样。

主要作用如下：

去重，把一个列表变成集合，就自动去重了

关系测试，测试两组数据之前的交集、差集、并集等关系

s = set([3,5,9,10])      #创建一个数值集合

t = set("Hello")         #创建一个唯一字符的集合

a = t | s          # t 和 s的并集

b = t & s          # t 和 s的交集

c = t – s          # 求差集（项在t中，但不在s中）

d = t ^ s          # 对称差集（项在t或s中，但不会同时出现在二者中）

基本操作：

t.add('x')            # 添加一项

s.update([10,37,42])  # 在s中添加多项

使用remove()可以删除一项：

t.remove('H')

len(s)
set 的长度

x in s
测试 x 是否是 s 的成员

x not in s
测试 x 是否不是 s 的成员

s.issubset(t)
s <= t
测试是否 s 中的每一个元素都在 t 中

s.issuperset(t)
s >= t
测试是否 t 中的每一个元素都在 s 中

s.union(t)
s | t
返回一个新的 set 包含 s 和 t 中的每一个元素

s.intersection(t)
s & t
返回一个新的 set 包含 s 和 t 中的公共元素

s.difference(t)
s - t
返回一个新的 set 包含 s 中有但是 t 中没有的元素

s.symmetric_difference(t)
s ^ t
返回一个新的 set 包含 s 和 t 中不重复的元素

s.copy()
返回 set “s”的一个浅复制

常用操作

交集(intersection)

两组列表中，取相同的值

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
print(list_1,type(list_1))

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#交集
print( list_1.intersection(list_2) )

执行结果：

{1, 3, 4, 5, 6, 7, 9} <class 'set'>
{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
{4, 6}

并集（union)

两个列表合并成一个，去掉重复的值

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
print(list_1,type(list_1))

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#并集
print(list_1.union(list_2))

执行结果：

{1, 3, 4, 5, 6, 7, 9} <class 'set'>
{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
{0, 1, 2, 3, 4, 5, 6, 7, 66, 9, 8, 22}

差集(difference)

只保留list1里面有的，list2中没有的值。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
print(list_1,type(list_1))

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#差集
print(list_1.difference(list_2))
14 print(list_2.difference(list_1))

执行结果：

{1, 3, 4, 5, 6, 7, 9} <class 'set'>
{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
{1, 3, 5, 7, 9}
4 {0,8,2,66,22}

对称差集（symmetric_difference）

把交集去掉了，留下的不是并集，把两个互相都没有的，取出来。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#反向差集
print(list_1.symmetric_difference(list_2))

执行结果：

{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
{0, 1, 2, 66, 3, 5, 8, 7, 9, 22}

isdisjoint

判断有没有交集，如果有返回False，否则返回True

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#子集
list_3 = set([1,3,7])
print(list_3.issubset(list_1))
print(list_1.issubset(list_3))

16 print("---------------------------------")
17 list_4 = set([5,6,8])
18 print(list_3.isdisjoint(list_4))

执行结果：

{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
True
False
---------------------------------
True

判断有没有交集，如果有返回False，否则返回True

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#子集
list_3 = set([1,3,7])
print(list_3.issubset(list_1))
print(list_1.issubset(list_3))

16 print("---------------------------------")
17 list_4 = set([5,6,7,8])
18 print(list_3.isdisjoint(list_4))

执行结果：

{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
True
False
4 ---------------------------------
5 False

子集(issubset)

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#差集
print( list_1.intersection(list_2))

#子集
list_3 = set([1,3,7])
print(list_3.issubset(list_1))
print(list_1.issubset(list_3))

执行结果：

{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
{4, 6}
True
False

交集、并集、差集、对称差集另一种用法

#交集(intersection)
print(list_1 & list_2)

#并集 union
print(list_2 | list_1)

#差集 difference (in list 1 but not in list 2)
print(list_1 - list_2)

#对称差集
print(list_1 ^ list_2)

常用操作

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author: nulige

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_2 = ([2,6,0,66,22,8,4])
print(list_1,list_2)

#添加一项(无序插入）
list_1.add(999)
print(list_1)

#添加多项
list_1.update([888,777,555])
print(list_1)

#pop (删除）
# Remove and teturn an arbitrary set element.
# 删除一个，并返回一个任意的
print(list_1.pop())
print(list_1.pop())
print(list_1.pop())
print(list_1.pop())

#discard
print( list_1.discard(888) )

执行结果：

{1, 3, 4, 5, 6, 7, 9} [2, 6, 0, 66, 22, 8, 4]
{1, 3, 4, 5, 6, 7, 999, 9}
{1, 3, 4, 5, 6, 7, 999, 9, 777, 555, 888}
1
3
4
5
None