python中的字典推導式

案例1：將字典dict1 = {“001”: “aa”, “002”: “bb”, “003”: “cc”}中的key和value互換成{‘aa’: ‘001’, ‘bb’: ‘002’, ‘cc’: ‘003’}

dict1 = {"001": "aa", "002": "bb", "003": "cc"}
dict2 = {}
for key, value in dict1.items():
    dict2[value] = key
print(dict2)

dict3 = {value: key for key, value in dict1.items()}
print(dict3)

案例2：將列表中list1 = [“aa”, “bb”, “cc”]的下標和值互換

list1 = ["aa", "bb", "bb"]
dict1 = {value: index for index, value in enumerate(list1)}
print(dict1)

輸出

{'aa': 0, 'bb': 2}

注意：會自動去重