Pythonic way for retrieving value for a nested dictionary.
Dave Angel
davea at davea.name
Tue Mar 5 02:20:51 EST 2013
On 03/05/2013 01:48 AM, Lowly Minion wrote:
> For a typical dict:
>
> i.e.
> d = { '1': 'a', '2', 'b' }
>
> I might use something like:
>
> d.get('1', None)
>
> To get the value of 1.
>
> What would be the most pythonic way of getting a nested value of a dictionary within a list:
>
> some_list = [{ 'item': { 'letter': 'b',
> 'word': 'bar' }},
> { 'item': { 'letter': 'c',
> 'word': 'charcoal' }}]
>
> Currently I am looping through the list as such:
>
> for item in some_list:
> print item['item']['letter']
>
> One other method explored was:
> item.get('item').get('letter')
>
> Is a double get the best way? Doesn't seem right to me.
>
> Thank you in advance for your help
>
I'm not sure what the puzzle is. Use [key] if you know the key exists,
and use get( key, default) if you don't. But be aware that if the first
key doesn't exist, then the default had better be a dict (rather than
something like None), or the second lookup will throw an exception, even
if you use get.
One other possibility, depending on just what you're doing with the
data, is to wrap it in a try/catch.
However, if you know exactly what the keys are, perhaps you should use a
namedtuple instead of a dict.
--
DaveA
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