字典dict
1.dic = {key:value,key:value}
字典有{ }括住,字典的value可以是任意值,字典的key的值不包括列表和字典
di = {"age":18,"name":"john","a":True,"b":[1,2,"movie"],"c":(1,2,"ff",)} print(di)
运算结果:
{'age': 18, 'name': 'john', 'a': True, 'b': [1, 2, 'movie'], 'c': (1, 2, 'ff')} Process finished with exit code 0
2.取值(只能通过索引的方式,不能用切片的方式。因为字典是无序的)
di = {"age":18,"name":"john","a":True,"b":[1,2,"movie"],"c":(1,2,"ff",)} v = di["c"][0] print(v)
运行结果:
1
Process finished with exit code 0
3.删除
di = {"age":18,"name":"john","a":True,"b":[1,2,"movie"],"c":(1,2,"ff",)} del di["b"][2] print(di)
运行结果:
{'age': 18, 'name': 'john', 'a': True, 'b': [1, 2], 'c': (1, 2, 'ff')} Process finished with exit code 0
4.循环(只能用for循环,不能用while,因为字典是无序的)
di = {"age":18,"name":"john","a":True,"b":[1,2,"movie"],"c":(1,2,"ff",)} for k,v in di.items(): print(k,v)
运行结果:
age 18 name john a True b [1, 2, 'movie'] c (1, 2, 'ff') Process finished with exit code 0
5.方法
-根据序列创建字典并指定统一的值
a= dict.fromkeys(["age",123,"465"],222) print(a)
运行结果:
{'age': 222, 123: 222, '465': 222} Process finished with exit code 0
-根据key取值,如果没有key,则为none
dic = {"a":1,"b":3} v = dic.get("a") print(v)
运行结果:
1
Process finished with exit code 0
-删除
dic = {"a":1,"b":3} v = dic.pop("a") print(v) print(dic)
运行结果:
1 {'b': 3} Process finished with exit code 0
-随机删除
dic = {"a":1,"b":3} v = dic.popitem() print("删除的值为:",v) print(dic)
运行结果:
删除的值为: ('b', 3) {'a': 1} Process finished with exit code 0
-设置,如果设置的值不存在,则创建新的,如果存在,不设置,直接获取当前的值
dic = {"a":1,"b":3} v = dic.setdefault("c",132) print(v) print(dic)
运行结果:
132 {'a': 1, 'b': 3, 'c': 132} Process finished with exit code 0
-添加
第一种方法:
dic = {"a":1,"b":3} v = dic.update({"c":"456"}) print(dic)
运行结果:
{'a': 1, 'b': 3, 'c': '456'} Process finished with exit code 0
第二种方法:
dic = {"a":1,"b":3} v = dic.update(c=123,d=456) print(dic)
运行结果:
{'a': 1, 'b': 3, 'c': 123, 'd': 456} Process finished with exit code 0