python3列表和字典排序

一、列表排序

1.1 列表排序list.sort,改变原始列表的顺序,reverse按降序排列

list.sort(key=None, reverse=False)

如下：所有学生成绩，按数学成绩排序

students = [{"name":"zhangsan1","math":"89","english":"87"},
            {"name":"zhangsan2","math":"65","english":"87"},
            {"name":"zhangsan3","math":"99","english":"87"},
            {"name":"zhangsan4","math":"55","english":"87"},
            ]
students.sort(key=lambda item: item.get('math'),reverse=True)
print(students)

1.2 列表排序sorted，不改变原始列表或字典的顺序，返回一个新的列表

sorted(iterable, key=None, reverse=False)

所有学生成绩，按数学成绩排序

students = [{"name":"zhangsan1","math":"89","english":"87"},
            {"name":"zhangsan2","math":"65","english":"87"},
            {"name":"zhangsan3","math":"99","english":"87"},
            {"name":"zhangsan4","math":"55","english":"87"},
            ]
result = sorted(students, key=lambda student:student['math'], reverse=True)
print(result)
print(students)

二、字典排序

2.1字典排序sorted，按key大小排序，返回一个元组，原始字典顺序不变

单个学生按分数排序的各科目

zhangsan = {"math":"89","english":"87","chinese":"99"}
result = sorted(zhangsan.items(), key=lambda item:item[1],reverse=True)
print(result)
print(zhangsan)