CODEWITHSUNDEEP
pythondictionary
jwang
jwang

Reputation: 25

Returning default value from a nested dict lookup in python

I'm trying to perform several lookups in a dictionary, some of which may be lookups to subdictionaries (d['a'], d['b']['c']['d']['e']). I'd like to return a default value on KeyError at any point in the lookup process, whether it be on the first or nth dictionary. The end goal is to put the return values in a new, flattened dictionary.

Is there a simpler way of doing this than my current:

e = {}
try:
    e['a'] = d['a']
except KeyError:
    e['a'] = 0
try:
    e['d'] = d['b']['c']['d']
except KeyError:
    e['d'] = 0

...and so on

I've thought about the issue some and considered using .get() or using defaultdict() or using some sort of recursion, but couldn't come up with any solutions. Thanks in advance for the help!

Upvotes: 0

Views: 218

Answers (1)

kindall
kindall

Reputation: 184191

Break that out into a function:

def try_get(dic, default, *keys):
    for key in keys:
        try:
            dic = dic[key]
        except KeyError:
            return default
    return dic

e['a'] = try_get(d, 0, 'a')
e['d'] = try_get(d, 0, 'b', 'c', 'd')

Upvotes: 2

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