| systems = [ {"book_type": "python", "book_name": "python小册"},
 {"book_type": "python", "book_name": "python学习手册"},
 {"book_type": "python", "book_name": "python编程"},
 {"book_type": "java", "book_name": "java编程实战"},
 {"book_type": "java", "book_name": "java并发编程"},
 ]
 from operator import itemgetter
 from itertools import groupby
 
 for book_type, item in groupby(systems, key=itemgetter("book_type")):
 print(book_type)
 for i in item:
 print("  ", i)
 
 |