Populating dictionary values from a list

Question

I'm trying to construct a dictionary in python. Code looks like this:

dicti = {}
keys = [1, 2, 3, 4, 5, 6, 7, 8, 9]
dicti = dicti.fromkeys(keys)

values = [2, 3, 4, 5, 6, 7, 8, 9]

How can I populate values of dictionary using a list? Is there some built in function?

The result should be like this:

dicti = {1:2,2:3,3:4,4:5,5:6,6:7,7:8,8:9}

@user1455966 You should use `dict.fromkeys` instead of using your dict's name to access that classmethod. — jamylak, Jul 13 '12 at 09:58
possible duplicate of [Map two lists into a dictionary in Python](http://stackoverflow.com/questions/209840/map-two-lists-into-a-dictionary-in-python) — Jeremy, Jul 14 '12 at 14:07

eumiro · Answer 1 · 2012-07-13T09:59:59.980

26

If you have two lists keys and the corresponding values:

keys = [1, 2, 3, 4, 5, 6, 7, 8, 9]
values = [2, 3, 4, 5, 6, 7, 8, 9]
dicti = dict(zip(keys, values))

dicti is now {1: 2, 2: 3, 3: 4, 4: 5, 5: 6, 6: 7, 7: 8, 8: 9}

edited Jul 13 '12 at 09:59

answered Jul 13 '12 at 09:48

eumiro

As a note, one should be careful when using zip. It is important to notice how `zip` drops values from the longer list. This example demonstrates what would happen if someone intended to have 9 corresponding key:value pairs but missed the first value from the `values` list. Notice how the values are actually shifted by one, e.g., value 2 ended up with key 1! This may not be the intended behavior. Be sure to check that the code matches what you actually intended. – Steven C. Howell Mar 20 '17 at 15:25

score 1 · Answer 2 · answered Sep 15 '20 at 07:04

1

Another one liner for your specific case would be:

dicti = {k:v for k, v in enumerate(values, start=1)}

The result is:

print(dicti)
{1:2,2:3,3:4,4:5,5:6,6:7,7:8,8:9}

answered Sep 15 '20 at 07:04

anjandash

score 0 · Answer 3 · answered Nov 17 '17 at 19:12

0

this will work but the list have to be the same size (drop the 9 in the keys list)

keys = [1, 2, 3, 4, 5, 6, 7, 8]
values = [2, 3, 4, 5, 6, 7, 8, 9]
dicti = {}

for x in range(len(keys)):
     dicti[keys[x]] = values[x]

answered Nov 17 '17 at 19:12

Rolando Silva

3 Answers3