列表嵌套字典，根据字典某一key排序

在返回列表嵌套字典时候，往往需要对数据进行一定的处理：
按照字典中某一个key排序

In [87]: a = [{"name": "牛郎", "age": 23},{"name":"许仙", "age": 20},{"name":"董永", "age": 18}]
In [88]: a
Out[88]:
[{‘name‘: ‘牛郎‘, ‘age‘: 23},
 {‘name‘: ‘许仙‘, ‘age‘: 20},
 {‘name‘: ‘董永‘, ‘age‘: 18}]
In [89]: a.sort(key=lambda x:(x[‘name‘], x[‘age‘]))  # 根据字典中name，age排序
In [90]: a
Out[90]:
[{‘name‘: ‘牛郎‘, ‘age‘: 23},
 {‘name‘: ‘董永‘, ‘age‘: 18},
 {‘name‘: ‘许仙‘, ‘age‘: 20}]
In [91]: a.sort(key=lambda x:(x[‘age‘], x[‘name‘]))
In [92]: a
Out[92]:
[{‘name‘: ‘董永‘, ‘age‘: 18},
 {‘name‘: ‘许仙‘, ‘age‘: 20},
 {‘name‘: ‘牛郎‘, ‘age‘: 23}]

如果排序字段是数字类型，如果我们需要对该字段进行逆序排，也可以这么写：

a.sort(key=lambd x :(x[‘name‘], -x[‘age‘]))

原文地址：http://blog.51cto.com/10412806/2174512