如何在OrderedDict中迭代OrderedDict

Question

嗨，我想解析一些order_dicts。我有以下错误

ipdb> for elem in my_orderdict['codeBook'].keys():
          print("{0}  ===> {1}".format(elem, my_orderdict[elem ]))
*** KeyError: '@xmlns'

因此，假设我创建了一个Orderdict，稍后我想要迭代该Orderdict以获得每个项和值。

ipdb >>> from collections import *
ipdb >>> my_orderdict = \
OrderedDict([('codeBook',
    OrderedDict([('@xmlns', 'http://www.johndoe.com'),
         ('@xmlns:xsi',
          'http://www.w3.org/2001/XMLSchema-instance'),
         ('@version', '1.2.2'),
         ('@ID', '_71M0001XCB-F-1991-novembre'),
         ('@xml-lang', 'en'),
         ('@xsi:schemaLocation', 'http://www.johndoe.xsd'),
         ('stdyDscr',
          OrderedDict([('stdyInfo',
              OrderedDict([('subject',
                  OrderedDict([('keyword',
                                ['Chômage',
                                 'Emploi'])]))]))]))]))])

ipdb >>> type(my_orderdict)
<class 'collections.OrderedDict'>

ipdb >>>  my_orderdict['codeBook'].keys()
odict_keys(['@xmlns', '@xmlns:xsi', '@version', 
            '@ID', '@xml-lang', '@xsi:schemaLocation', 'stdyDscr'])

我正在创建一个循环来访问每个odict_keys的值

for elem in my_orderdict['codeBook'].keys():
    print("{0}  ===> {1}".format(elem, my_orderdict[elem ]))

我想要的结果应该是

@xmlns ===> 'http://www.johndoe.com'
@xmlns:xsi ===> 'http://www.w3.org/2001/XMLSchema-instance'
@version ===> 1.2.2
...

这样我就可以解析这个命令了。现在我的错误是：

ipdb> for elem in my_orderdict['codeBook'].keys():
          print("{0}  ===> {1}".format(elem, my_orderdict[elem ]))
*** KeyError: '@xmlns'

所以我无法访问我的第一个orderdict的属性。

Answer 1

看起来你的循环没有访问正确的字典。您应该使用：

for elem in my_orderdict['codeBook'].keys():
    print("{0}  ===> {1}".format(elem, my_orderdict['codeBook'][elem ]))

注意内部循环中的my_orderdict['codeBook']。

基本上:您正在迭代字典my_orderdict['codeBook']的元素，但试图直接访问my_orderdict的值。

希望这能有所帮助！

Answer 2

您正在遍历subdict的键：for elem in my_orderdict['codeBook'].keys():，但是在parent-dict：my_orderdict[elem ]上使用这些键需要使用my_orderdict['codeBook']，因此：

In [2]: data = OrderedDict([('codeBook',
   ...:     OrderedDict([('@xmlns', 'http://www.johndoe.com'),
   ...:          ('@xmlns:xsi',
   ...:           'http://www.w3.org/2001/XMLSchema-instance'),
   ...:          ('@version', '1.2.2'),
   ...:          ('@ID', '_71M0001XCB-F-1991-novembre'),
   ...:          ('@xml-lang', 'en'),
   ...:          ('@xsi:schemaLocation', 'http://www.johndoe.xsd'),
   ...:          ('stdyDscr',
   ...:           OrderedDict([('stdyInfo',
   ...:               OrderedDict([('subject',
   ...:                   OrderedDict([('keyword',
   ...:                                 ['Chômage',
   ...:                                  'Emploi'])]))]))]))]))])

In [3]: for elem in data['codeBook']: #note, call to .keys is not necessary
   ...:     print("{0} ===> {1}".format(elem, data['codeBook'][elem]))
   ...:
@xmlns ===> http://www.johndoe.com
@xmlns:xsi ===> http://www.w3.org/2001/XMLSchema-instance
@version ===> 1.2.2
@ID ===> _71M0001XCB-F-1991-novembre
@xml-lang ===> en
@xsi:schemaLocation ===> http://www.johndoe.xsd
stdyDscr ===> OrderedDict([('stdyInfo', OrderedDict([('subject', OrderedDict([('keyword', ['Chômage', 'Emploi'])]))]))])

但是，在这种情况下，您可以只使用items，它遍历键-值对

In [4]: for k, v  in data['codeBook'].items():
   ...:     print("{0} ===> {1}".format(k, v))
   ...:
@xmlns ===> http://www.johndoe.com
@xmlns:xsi ===> http://www.w3.org/2001/XMLSchema-instance
@version ===> 1.2.2
@ID ===> _71M0001XCB-F-1991-novembre
@xml-lang ===> en
@xsi:schemaLocation ===> http://www.johndoe.xsd
stdyDscr ===> OrderedDict([('stdyInfo', OrderedDict([('subject', OrderedDict([('keyword', ['Chômage', 'Emploi'])]))]))])