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I'm building a crawler to extract data and I'm having trouble categorizing it all when I get it. It seems that the dict key I was expecting to use will not pull what I am looking for. I want to extract "member_id" and "vote_position".

The example below shows an attempt to pull using the "positions" key. Using "positions", "member_id", "vote_position" all yield the same KeyError.

Moving farther down you can see the output when using print data. Still, using the keys displayed after print data output still yields KeyError.

I'm feeling pretty stumped. Any help would be greatly appreciated.

import urllib2
import json
api_key = '72c9a68****************************'
url = 'http://api.time.com/svc/politics/v3/us/legislative/blue/113/
json_obj = urllib2.urlopen(url)
data = json.load(json_obj)

print data['positions']

Traceback (most recent call last):
  File "/Users/Owner/PycharmProjects/untitled2/1", line 8, in <module>
  print data [positions]
NameError: name 'positions' is not defined

JSON Data:

 "positions": [
          {
            "member_id": "A000055",
            "vote_position": "Yes",
            "dw_nominate": "0.466"
          },
                        {
            "member_id": "A000367",
            "vote_position": "Yes",
            "dw_nominate": "0.995"
          },

a simple print data yields:

{u'dw_nominate': u'-0.311', u'vote_position': u'Yes', u'member_id': u'B001242'},     {u'dw_nominate': u'0.793', u'vote_position': u'Yes', u'member_id': u'B001250'}, {u'dw_nominate': u'0.728', u'vote_position': u'Yes', u'member_id': u'B001273'}
4

2 回答 2

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如果这是“ positions”项不存在或某处拼写错误的简单情况，您将收到如下错误：

KeyError: 'positions'

相反，NameError您看到的是告诉您positions尚未定义名为的变量。Python 试图引用具有该名称的变量，而不是使用字符串，因为这行说：

print data [positions]

缺少单词周围的引号。

（至少根据您的回溯：）

Traceback (most recent call last):
  File "/Users/Owner/PycharmProjects/untitled2/1", line 8, in <module>
  print data [positions]
于 2014-12-29T04:27:44.233 回答
0

从你给的：

data = {u'dw_nominate': u'-0.311', u'vote_position': u'Yes', u'member_id': u'B001242'},     {u'dw_nominate': u'0.793', u'vote_position': u'Yes', u'member_id': u'B001250'}, {u'dw_nominate': u'0.728', u'vote_position': u'Yes', u'member_id': u'B001273'}

print type(data) # returns tuple

data[0]['vote_position'] # returns 'Yes'

获取所有密钥：

for i in xrange(len(data)): # python 2.x, for python 3, use range()
    print data[i].keys()
于 2014-12-29T04:23:44.943 回答