标签：适合 title 合并 存在 删除 key 变化 for循环 lis
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
标签：适合 title 合并 存在 删除 key 变化 for循环 lis
原文地址：https://www.cnblogs.com/huiguizhe/p/11988302.html
