CODEWITHSUNDEEP
pythondictionary
Karthick
Karthick

Reputation: 4766

How to construct a defaultdict from a dictionary?

If I have d=dict(zip(range(1,10),range(50,61))) how can I build a collections.defaultdict out of the dict?

The only argument defaultdict seems to take is the factory function, will I have to initialize and then go through the original d and update the defaultdict?

Upvotes: 119

Views: 60117

Answers (3)

muhsin mohammed
muhsin mohammed

Reputation: 301

You can construct a defaultdict from dict, by passing the dict as the second argument.

from collections import defaultdict

d1 = {'foo': 17}
d2 = defaultdict(int, d1)

print(d2['foo'])  ## should print 17
print(d2['bar'])  ## should print 0 (int() returns 0)

Upvotes: 20

hoi ja
hoi ja

Reputation: 267

You can create a defaultdict with a dictionary by using a callable.

from collections import defaultdict

def dict_():
    return {'foo': 1}

defaultdict_with_dict = defaultdict(dict_)

Upvotes: -1

Jochen Ritzel
Jochen Ritzel

Reputation: 107598

Read the docs:

The first argument provides the initial value for the default_factory attribute; it defaults to None. All remaining arguments are treated the same as if they were passed to the dict constructor, including keyword arguments.

from collections import defaultdict
d=defaultdict(int, zip(range(1,10),range(50,61)))

Or given a dictionary d: 

from collections import defaultdict
d=dict(zip(range(1,10),range(50,61)))
my_default_dict = defaultdict(int,d)

Upvotes: 130

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