python sort list of json by value

Question

I have a file consists of JSON, each a line, and want to sort the file by update_time reversed.

sample JSON file:

{ \"page\": { \"url\": \"url1\", \"         


        

Answer 1

You can use dict.get() with a default value:

lines = sorted(lines, key=lambda k: k['page'].get('update_time', 0), reverse=True)

Example:

>>> lines = [
...     {"page": {"url": "url1", "update_time": "1415387875"}, "other_key": {}},
...     {"page": {"url": "url2", "update_time": "1415381963"}, "other_key": {}},
...     {"page": {"url": "url3", "update_time": "1415384938"}, "other_key": {}},
...     {"page": {"url": "url4"}, "other_key": {}},
...     {"page": {"url": "url5"}, "other_key": {}}
... ]
>>> lines = sorted(lines, key=lambda k: k['page'].get('update_time', 0), reverse=True)
>>> for line in lines:
...     print line
... 
{'other_key': {}, 'page': {'url': 'url1', 'update_time': '1415387875'}}
{'other_key': {}, 'page': {'url': 'url3', 'update_time': '1415384938'}}
{'other_key': {}, 'page': {'url': 'url2', 'update_time': '1415381963'}}
{'other_key': {}, 'page': {'url': 'url4'}}
{'other_key': {}, 'page': {'url': 'url5'}}

Though, I would still follow the EAFP principle that Ferdinand suggested - this way you would also handle cases when page key is also missing. Much easier to let it fail and handle it than checking all sorts of corner cases.