Python implements sorting of custom class objects (using attrgetter)

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1. Requirements

Sort the list of custom classes.

2. Solution

The built-in sorted() function can accept a parameter key used to pass a callable object (callable), and the callable object will return to be Certain values ​​in an object are sorted, and sorted uses these values ​​to compare the objects.

Example:

from operator import attrgetter
class User:
def __init__(self,userId):
self.userId=userId

def __repr__(self):
return 'User({})'.format(self.userId)

users=[User(40),User(20),User(30)]
print(users)

#方法1
print(sorted(users,key=lambda u:u.userId))

#方法2
print(sorted(users,key=attrgetter('userId')))

Running result:

[User(40), User(20), User(30)]
[User(20), User(30), User(40)]
[User(20), User(30), User(40)]

attrgetter is usually a little faster. The above counting also applies to the min() and max() functions.

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