dict1 = {
"key1": 1,
"key2": 2,
"key3": 3,
}
print(type(dict1)) # <class 'dict'>
print(type(dict1) == dict) # True
print(isinstance(dict, dict)) # False
print(len(dict1)) # 3
print(dict1) # {'key1': 1, 'key2': 2, 'key3': 3}
# 访问元素
print(dict1["key1"]) # 1
# print(dict1["key4"]) # key不存在会抛异常
print(dict1.get("key4")) # None, key不存在返回默认值
# 添加元素(不存在的key)
dict1["key4"] = 4
print(dict1) # {'key1': 1, 'key2': 2, 'key3': 3, 'key4': 4}
print(len(dict1)) # 4
# 修改元素(已存在的key)
dict1["key3"] = 30
print(dict1) # {'key1': 1, 'key2': 2, 'key3': 30, 'key4': 4}
# 删除元素
del dict1["key4"]
print(dict1) # {'key1': 1, 'key2': 2, 'key3': 30}
elem = dict1.pop("key3")
print(dict1) # {'key1': 1, 'key2': 2}
# elem = dict1.pop("key6") # 删除不存在的key会抛异常
# 查找key
print("key1" in dict1) # True
print("key4" in dict1) # False
dict1 = {
"key1": 1,
"key2": 2,
}
# 遍历
for k in dict1:
print(k, dict1[k])
for k, v in dict1.items():
print(k, v)
print(dict1.keys()) # dict_keys(['key1', 'key2'])
print(dict1.values()) # dict_values([1, 2])
print(dict1.items()) # dict_items([('key1', 1), ('key2', 2)])
list1 = ["a", "b", "c"]
dict1 = dict.fromkeys(list1, 1) # list元素作为key创建dict, 所有键的值填充为1
print(dict1) # {'a': 1, 'b': 1, 'c': 1}