Python 类型错误：“int”对象没有属性“__getitem__”错误，因为书中可能存在错误
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TypeError: 'int' object has no attribute '__getitem__' error because of possible erratum in book
提问by megashigger
I'm going through the new book "Data Science from Scratch: First Principles with Python" and I think I've found an errata.
我正在阅读新书“从头开始的数据科学：Python 的首要原则”，我想我找到了一个勘误表。
When I run the code I get "TypeError: 'int' object has no attribute '__getitem__'".I think this is because when I try to select friend["friends"], friendis an integer that I can't subset. Is that correct? How can I continue the exercises so that I get the desired output? It should be a list of friend of friends (foaf). I know there's repetition problems but those are fixed later...
当我运行代码时，我"TypeError: 'int' object has no attribute '__getitem__'".认为这是因为当我尝试选择时friend["friends"]， ,friend是一个我不能子集的整数。那是对的吗？我怎样才能继续练习以获得所需的输出？它应该是朋友的朋友列表（foaf）。我知道存在重复问题，但这些问题稍后会修复...
users = [
{"id": 0, "name": "Ashley"},
{"id": 1, "name": "Ben"},
{"id": 2, "name": "Conrad"},
{"id": 3, "name": "Doug"},
{"id": 4, "name": "Evin"},
{"id": 5, "name": "Florian"},
{"id": 6, "name": "Gerald"}
]
#create list of tuples where each tuple represents a friendships between ids
friendships = [(0,1), (0,2), (0,5), (1,2), (1,5), (2,3), (2,5), (3,4), (4,5), (4,6)]
#add friends key to each user
for user in users:
user["friends"] = []
#go through friendships and add each one to the friends key in users
for i, j in friendships:
users[i]["friends"].append(j)
users[j]["friends"].append(i)
def friends_of_friend_ids_bad(user):
#foaf is friend of friend
return [foaf["id"]
for friend in user["friends"]
for foaf in friend["friends"]]
print friends_of_friend_ids_bad(users[0])
Full traceback:
完整追溯：
Traceback (most recent call last):
File "/Users/marlon/Desktop/test.py", line 57, in <module>
print friends_of_friend_ids_bad(users[0])
File "/Users/marlon/Desktop/test.py", line 55, in friends_of_friend_ids_bad
for foaf in friend["friends"]]
TypeError: 'int' object has no attribute '__getitem__'
[Finished in 0.6s with exit code 1]
[shell_cmd: python -u "/Users/marlon/Desktop/test.py"]
[dir: /Users/marlon/Desktop]
[path: /usr/bin:/bin:/usr/sbin:/sbin]
How I think it can be fixed: I think you need users as a second argument and then do "for foaf in users[friend]["friends"]" instead of "for foaf in friend["friends"]
我认为如何解决：我认为您需要用户作为第二个参数，然后执行“for foaf in users[friend]["friends"]”而不是“for foaf infriend["friends"]
采纳答案by Alik
Yes, you've found an incorrect piece of code in the book.
是的，您在书中发现了一段不正确的代码。
Implementation for friends_of_friend_ids_badfunction should be like this:
friends_of_friend_ids_bad函数的实现应该是这样的：
def friends_of_friend_ids_bad(user):
#foaf is friend of friend
return [users[foaf]["id"]
for friend in user["friends"]
for foaf in users[friend]["friends"]]
user["friends"]is a list of integers, thus friendis an integer and friend["friends"]will raise TypeErrorexception
user["friends"]是一个整数列表，因此friend是一个整数并且friend["friends"]会引发TypeError异常
UPD
UPD
It seems, that the problem in the book was not about friends_of_friend_ids_badfunction but about populating friendslists.
看来，书中的问题不在于friends_of_friend_ids_bad函数，而在于填充friends列表。
Replace
代替
for i, j in friendships:
users[i]["friends"].append(j)
users[j]["friends"].append(i)
with
和
for i, j in friendships:
users[i]["friends"].append(users[j])
users[j]["friends"].append(users[i])
Then friends_of_friend_ids_badand friends_of_friend_idswill work as intended.
然后friends_of_friend_ids_bad，friends_of_friend_ids将按预期工作。
回答by Ericson Willians
The error is on:
错误是：
return [foaf["id"] for friend in user["friends"] for foaf in friend["friends"]]
In the second for loop, you're trying to access __getitem__of users[0]["friends"], which is exactly 5 (ints don't have __getitem__).
在第二个 for 循环中，您尝试访问__getitem__of users[0]["friends"]，正好是 5（整数没有__getitem__）。
You're trying to store on the list foaf["id"]for each friend in user["friends"]and for each foaf friend["friends"]. The problem is that foaf gets from friend["friends"]the number from a tuple inside friendships that was stored on users, and then you try to access ["id"]from it, trying to call __getitem__from an integer value.
您正在尝试foaf["id"]为每个朋友user["friends"]和每个 foaf存储在列表中friend["friends"]。问题是 foaf 从friend["friends"]存储在用户中的友谊内部的元组中获取数字，然后您尝试从中访问["id"]，尝试__getitem__从整数值调用。
That's the exact cause of your problem.
这就是您问题的确切原因。
