在python中有一個對象數組，我如何通過屬性對它的元素進行分類？

Question

在Python中，是否有一個函數按屬性對對象數組進行分類和排序？

例子：

class Book: 
    """A Book class""" 
    def __init__(self,name,author,year): 
     self.name = name 
     self.author = author 
     self.year = year 

hp1 = Book("Harry Potter and the Philosopher's stone","J.k Rowling",1997) 
hp2 = Book("Harry Potter and the chamber of secretse","J.k Rowling",1998) 
hp3 = Book("Harry Potter and the Prisioner of Azkaban","J.k Rowling",1999) 

#asoiaf stands for A Song of Ice and Fire 
asoiaf1 = Book("A Game of Thrones","George R.R Martin",1996) 
asoiaf2 = Book("A Clash of Kings","George R.R Martin",1998) 

hg1 = Book("The Hunger Games","Suzanne Collins",2008) 
hg2 = Book("Catching Fire","Suzanne Collins",2009) 
hg3 = Book("Mockingjaye","Suzanne Collins",2010); 

books = [hp3,asoiaf1,hp1,hg1,hg2,hp2,asoiaf2,hg3] 
#disordered on purpose 

organized_by_autor = magic_organize_function(books,"author") 

的magic_organize_function存在嗎？否則，它會是什麼？

Answer 1

按作者排序是單向的：

sorted_by_author = sorted(books, key=lambda x: x.author) 
for book in sorted_by_author: 
    print(book.author) 

輸出：

George R.R Martin 
George R.R Martin 
J.k Rowling 
J.k Rowling 
J.k Rowling 
Suzanne Collins 
Suzanne Collins 
Suzanne Collins 

您還可以通過作者很好地組使用itertools.groupby：

from itertools import groupby 

organized_by_author = groupby(sorted_by_author, key=lambda x: x.author) 

for author, book_from_author in organized_by_author: 
    print(author) 
    for book in book_from_author: 
     print(' ', book.name) 

輸出：

George R.R Martin 
    A Game of Thrones 
    A Clash of Kings 
J.k Rowling 
    Harry Potter and the Prisioner of Azkaban 
    Harry Potter and the Philosopher's stone 
    Harry Potter and the chamber of secretse 
Suzanne Collins 
    The Hunger Games 
    Catching Fire 
    Mockingjaye 

注意：您需要飼料groupby排序sorted_by_author。