列表理解错误输出

Question

data = [

[
    {'name': 'gan', 'age': 21}, {'name': 'esh', 'age': 22}
],

[
    {'name': 'rahul', 'age': 23}, {'name': 'rohan', 'age': 24}
]

]
u_names = [data['name'] for i in data for j in i if data['age'] > 21]
print(u_names)


line 38, in <module>
    if data['age'] > 21:
TypeError: list indices must be integers or slices, not str

我犯了这个错误，原因是什么

Answer 1

更改为：

u_names = [j['name'] for i in data for j in i if j['age'] > 21]

data是一个嵌套列表j是内部实际迭代的dict对象

如果将对象重命名为更具描述性，则会看到结构：

u_names = [
    inner_dict['name']
        for inner_list in data
            for inner_dict in inner_list
                if inner_dict['age'] > 21
    ]

也就是说：

for inner_list in data:
    for inner_dict in inner_list:
        if inner_dict['age'] > 21:
            return inner_dict['name']

Answer 2

请尝试以下操作：

u_names = [j['name'] 
for i in data:
    for j in i:
         if j['age'] > 21:
             print(u_names)

通过访问data['name']，您试图访问原始数据数组上的属性name，而不是在您的理解中分配给i的子数组