python之sort高级用法

来源：互联网发布：淘宝黑科技编辑：程序博客网时间：2024/06/04 01:16

both list.sort() and sorted() added a key parameter to specify a FUNCTION to be called on each list element prior to making comparisons.

而且通过通过设置reverse可以颠倒排序结果

#注意key后的是function，不是function call的值, 所以常用lambda表达式sorted("This is a test string".split(), key=str.lower)----------------------------------------['This', 'test', 'string', 'is', 'a']#A common pattern is to sort complex objects using some of the object’s indices as keysstudent_tuples = [('john', 'A', 15),('jane', 'B', 12),('dave', 'B', 10),]sorted(student_tuples, key=lambda student: student[2])----------------------------------------[('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]#The same technique works for objects with named attributesclass Student(object):    def __init__(self, name, grade, age):        self.name = name        self.grade = grade        self.age = age    def __repr__(self):        return repr((self.name, self.grade, self.age))student_objects = [Student('John', 'A', 15), Student('Jane', 'B', 12), Student('Dave', 'B', 10),]sorted(student_objects, key=lambda student: student.age)------------------------------------------[('Dave', 'B', 10), ('Jane', 'B', 12), ('John', 'A', 15)]#上面都可以一些python内置的函数from operator import itemgetter, attrgettersorted(student_tuples, key=itemgetter(2))sorted(student_objects, key=attrgetter('age'))sorted(student_tuples, key=itemgetter(1,2))sorted(student_objects, key=attrgetter('grade', 'age'))

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