Retrieve item deep in dict tree?
Rustom Mody
rustompmody at gmail.com
Wed Apr 2 22:41:33 EDT 2014
On Wednesday, April 2, 2014 11:28:16 PM UTC+5:30, Roy Smith wrote:
> I have a big hairy data structure which is a tree of nested dicts. I have a sequence of strings which represents a path through the tree. Different leaves in the tree will be at different depths (which range from 1 to about 4 or 5 at most). I want to get the value stored at that path. Thus, if
> keys = ['foo', 'bar', 'baz']
> I want to retrieve tree['foo']['bar']['baz'].
> Is there some idiomatic, non-cryptic way to write that as a one-liner?
> I'm using Python 2.7.
What you are asking for is probably:
>>> reduce((lambda tr, att: tr[att]), ['a','b','c'], nested)
'Hiii!!'
>>>
I used a nested thus
>>> nested = {'a':{'b':{'c':"Hiii!!"}}}
But what you are REALLY looking for is what Steven/Gordon gave <wink>
In order to see more visibly that those whiles are just reduces
you may want to rewrite as:
>>> reduce((lambda tr, att: str(tr) + "[" + str(att) + "]"), ['a','b','c'], "nested")
'nested[a][b][c]'
IOW the 'theorem' I am using is that
reduce(op, id, l)
is short for
while l:
id, l = op(id, l[0]), l[1:]
return id
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