python列表推导和字典推导

代码如下：

list = ['aaa','bbb','ccc','ddd']
dict = {key:value for value,key in enumerate(list)}
print(dict)
# 字典交换key和value
reversed_dict = {value:key for key,value in dict.items()}
print(reversed_dict)

结果如下：

{'ddd': 3, 'ccc': 2, 'bbb': 1, 'aaa': 0}
{0: 'aaa', 1: 'bbb', 2: 'ccc', 3: 'ddd'}