CODEWITHSUNDEEP
pythonpython-3.x
cjm2671
cjm2671

Reputation: 19466

Map over a dict

I'm trying to do this:

list(map(lambda x: x.name, my_dict))

where my_dict is a dict of form k, v where v is an object and v.name is defined.

The problem is it is using the key k for x where I really want to use the value v.

In other words: How do I map over the values of a dict?

PS I want to avoid my_dict[x] as I will be using concurrent.futures and won't be passing the full dict into separate threads.

Upvotes: 6

Views: 5043

Answers (2)

Łukasz Rogalski
Łukasz Rogalski

Reputation: 23213

To retrieve view of values, you may use .values method.

map(callable, my_dict.values())

Obviously, map with trivial callables usually can be avoided in Python by using list or generator comprehensions.

[x.name for x in my_dict.values()]  # creates list: non-lazy
(x.name for x in my_dict.values())  # creates generator: lazy

Upvotes: 6

Kasravnd
Kasravnd

Reputation: 107287

You don't need to use map() and then convert the result to a list. Instead you can use simply use a list comprehension by looping over the dictionary values:

[v.name for v in my_dict.values()]

Or still if you are looking for a functional approach you can use attrgetter function from operator module :

from operator import attrgetter
map(attrgetter('name'), my_dict.values())

Upvotes: 3

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