title: Extract part of data from JSON file with python
body: <p>I have been trying to extract only certain data from a JSON file. I managed to decode the JSON and get the wanted data into a python dict. When I print out the dict it shows all the wanted data, but when I try to write the dict into a new file, only the last object gets written. 
  One thing that I can't understand is also why when I print the dict I get multiple dicts objects instead of 1 as I would expect.</p>
  
  <p>My code:</p>
  
  <pre><code>import json
  input_file=open('json.json', 'r')
  output_file=open('test.json', 'w')
  json_decode=json.load(input_file)
  for item in json_decode:
      my_dict={}
      my_dict['title']=item.get('labels').get('en').get('value')
      my_dict['description']=item.get('descriptions').get('en').get('value')
      my_dict['id']=item.get('id')
      print my_dict
  back_json=json.dumps(my_dict, output_file)
  output_file.write(back_json)
  output_file.close() 
  </code></pre>
  
  <p>my json.json file:</p>
  
  <pre><code>[
  {"type":"item","labels":{"en":{"language":"en","value":"George Washington"}},"descriptions":{"en":{"language":"en","value":"American politician, 1st president of the United States (in office from 1789 to 1797)"}},"id":"Q23"},
  {"type":"item","aliases":{"en":[{"language":"en","value":"Douglas Noël Adams"},{"language":"en","value":"Douglas Noel Adams"}]},"labels":{"en":{"language":"en","value":"Douglas Adams"}},"descriptions":{"en":{"language":"en","value":"English writer and humorist"}},"id":"Q42"},
  {"type":"item","aliases":{"en":[{"language":"en","value":"George Bush"},{"language":"en","value":"George Walker Bush"}]},"labels":{"en":{"language":"en","value":"George W. Bush"}},"descriptions":{"en":{"language":"en","value":"American politician, 43rd president of the United States from 2001 to 2009"}},"id":"Q207"},
  {"type":"item","aliases":{"en":[{"language":"en","value":"Velázquez"},{"language":"en","value":"Diego Rodríguez de Silva y Velázquez"}]},"labels":{"en":{"language":"en","value":"Diego Velázquez"}},"descriptions":{"en":{"language":"en","value":"Spanish painter who was the leading artist in the court of King Philip IV"}},"id":"Q297"},
  {"type":"item","labels":{"en":{"language":"en","value":"Eduardo Frei Ruiz-Tagle"}},"descriptions":{"en":{"language":"en","value":"Chilean politician and former President"}},"id":"Q326"}
  ]
  </code></pre>
  
  <p>print my_dict output:</p>
  
  <pre><code>{'id': u'Q23', 'description': u'American politician, 1st president of the United States (in office from 1789 to 1797)', 'title': u'George Washington'}
  {'id': u'Q42', 'description': u'English writer and humorist', 'title': u'Douglas Adams'}
  {'id': u'Q207', 'description': u'American politician, 43rd president of the United States from 2001 to 2009', 'title': u'George W. Bush'}
  {'id': u'Q297', 'description': u'Spanish painter who was the leading artist in the court of King Philip IV', 'title': u'Diego Vel\xe1zquez'}
  {'id': u'Q326', 'description': u'Chilean politician and former President', 'title': u'Eduardo Frei Ruiz-Tagle'}
  </code></pre>
  
  <p>output in the file test.json:</p>
  
  <pre><code>{"id": "Q326", "description": "Chilean politician and former President", "title": "Eduardo Frei Ruiz-Tagle"}
  </code></pre>
  
  <p>Also I would like to know why the dict is outputing 'title': u'Diego Vel\xe1zquez'
  but if i go print my_dict.values()[2] i Get the name written normaly as Diego Velázquez. </p>
  
  <p>Many thanks</p>