二.列表，元组，集合，字典的基础应用

Posted 2021-03-23 huiguizhe

1.列表的应用(list [ ] 非常适合用于存储在程序运行期间可能变化的数据集)

1.1 range()函数

Experiments = []
for Experiment in range(1,10):
   Experiments.append(Experiment**2)
  print(Experiments)
>>[1, 4, 9, 16, 25, 36, 49, 64, 81]

1.2 列表解析将for循环和创建新元素的代码合并成一行，并自动附加新元素

Experiments =[value**2 for value in range(1,10)]
print(Experiments)
>>[1, 4, 9, 16, 25, 36, 49, 64, 81]

1.3 切片和遍历切片

players = [‘football‘,‘basketball‘,‘tennis‘]
print("I like playing:")
for player in players:
    print(player.title())

1.4 复制列表

players_one = players[:]

1.5 format()

name = ‘{n} like playing football‘.format(n=‘alex‘)
print(name)
>>alex like playing football

 

2.元组（tuple（） 不可改）

2.1 遍历

 

name = ( ‘liu‘,‘li‘)
for i in name:
    print(i)
>>liu
>>li

 

2.2 索引

 

name = ( ‘liu‘,‘li‘)
print(name[0])

2.3 运算符也可以(加，乘，以及len())

name = ( ‘liu‘,‘li‘)
number =(1,2)
print(name + number)
>>(‘liu‘, ‘li‘, 1, 2)

3.集合（set{}，去重，关系测试，无序）

3.1 关系测试

set_one = { 1,4,6}
set_two = {1, 5,"a" }
print(set_one.intersection(set_two))#交集
print(set_one & set_two)#进阶
>>{1}
>>{1}
print(set_one.difference(set_two))#差集
print(set_one - set_two)
>>{4, 6}
>>{4, 6}
print(set_one.union(set_two))#并集
print(set_one | set_two)
>>{1, ‘a‘, 4, 5, 6}
>>{1, ‘a‘, 4, 5, 6}
print(set_ont ^ set_two)#去重复并集

 3.2 集合添加

set_two = {1, 5,"a" }
set_two.add(13)#只能单个添加
print(set_two)
>>{‘a‘, 1, 13, 5}
set_two.update([14,"apple"])#多个添加
print(set_two)
>>{1, 5, ‘apple‘, 13, 14, ‘a‘}
set_two.update({23},["jiu"])#测试
print(set_two)
>>{1, 5, 23, ‘jiu‘, ‘a‘, 13}

3.3集合删除

set_two = {1, 5,"a" }
set_two.remove(5)#指定删除元素 ，不存在报错
print(set_two)
>>{1, ‘a‘}
set_two.discard(5)#也是指定删除元素，不存在不报错

set_two.pop()#随机删除一个

4.字典（dict() 是无序的，且key唯一，天生去重）

 4.1 打印和替换

info = {"key1":"value1",
        "key2":"value2"}
print(info["key1"])#打印key1的值，没有则报错
>>value1
info["key1"] = "值1"#替换或添加
print(info)
>>{‘key1‘: ‘值1‘, ‘key2‘: ‘value2‘}

4.2 删除键值对

info = {"key1":"value1",
        "key2":"value2"}
info.pop("key1")#删除键值对
print(info)
>>{‘key2‘: ‘value2‘}

del info["key1"]#del 删除键值对
print(info)

info.popitm()#随机删除

4.3

info = {"key1":"value1",
        "key2":"value2"}
for i in  info:
    print(i , info[i])
>>key1 value1
>>key2 value2

for k,v in info.items():#info.items,先把info改为列表再赋值
    print(k,v)
>>key1 value1
>>key2 value2