How find all childrens values of a nested dictionary, fast!

Arnaud Delobelle arnodel at gmail.com
Thu Nov 4 17:20:04 EDT 2010


macm <moura.mario at gmail.com> writes:

> Hi Folks
>
> How find all childrens values of a nested dictionary, fast!
>
>>>> a = {'a' : {'b' :{'/' :[1,2,3,4], 'ba' :{'/' :[41,42,44]} ,'bc' :{'/':[51,52,54], 'bcd' :{'/':[68,69,66]}}},'c' :{'/' :[5,6,7,8]}}, 'ab' : {'/' :[12,13,14,15]}, 'ac' :{'/' :[21,22,23]}}
>>>> a['a']
> {'c': {'/': [5, 6, 7, 8]}, 'b': {'ba': {'/': [41, 42, 44]}, '/': [1,
> 2, 3, 4], 'bc': {'bcd': {'/': [68, 69, 66]}, '/': [51, 52, 54]}}}
>>>> a['a']['b']
> {'ba': {'/': [41, 42, 44]}, '/': [1, 2, 3, 4], 'bc': {'bcd': {'/':
> [68, 69, 66]}, '/': [51, 52, 54]}}
>>>> a['a']['b'].values()
> [{'/': [41, 42, 44]}, [1, 2, 3, 4], {'bcd': {'/': [68, 69, 66]}, '/':
> [51, 52, 54]}]
>
> Now I want find all values of key "/"
>
> Desire result is [41, 42, 44, 1, 2, 3, 4, 68, 69, 66, 51, 52, 54]
>
> I am trying map, reduce, lambda.

Tough requirement, but I think I've got it.  Two lambdas, one reduce,
one map ;)

>>> a = {'a' : {'b' :{'/' :[1,2,3,4], 'ba' :{'/' :[41,42,44]}, 'bc' :{'/':[51,52,54], 'bcd' :{'/':[68,69,66]}}},'c' :{'/' :[5,6,7,8]}},'ab' : {'/' :[12,13,14,15]}, 'ac' :{'/' :[21,22,23]}}
>>> f = lambda v,k=None: v if k=="/" else reduce(list.__add__, map(lambda k: f(v[k],k), v), []) 
>>> f(a)
[5, 6, 7, 8, 41, 42, 44, 1, 2, 3, 4, 68, 69, 66, 51, 52, 54, 21, 22, 23, 12, 13, 14, 15]

This doesn't correspond with your desire result though.

-- 
Arnaud



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