python字典顺序转字符串

普通字典默认是无序的：

比如：

1 a = {‘b‘: 1, ‘a‘: 2}
2 print a
3 print repr(a)

输出：

1 {‘a‘: 2, ‘b‘: 1}
2 {‘a‘: 2, ‘b‘: 1}

有序的字典需要用到OrderedDict：

1 from collections import OrderedDict
2 a = OrderedDict()
3 a[‘b‘] = 2
4 a[‘a‘] = 1
5 print a
6 print repr(a)

输出：

1 OrderedDict([(‘b‘, 2), (‘a‘, 1)])
2 OrderedDict([(‘b‘, 2), (‘a‘, 1)])

用json的dumps方法将有序字典转为字符串：

1 from collections import OrderedDict
2 from json import dumps
3 a = OrderedDict()
4 a[‘b‘] = 2
5 a[‘a‘] = 1
6 print a
7 print dumps(a)

输出：

1 OrderedDict([(‘b‘, 2), (‘a‘, 1)])
2 {"b": 2, "a": 1}