Get first element of sublist as dictionary key in python

Question

I looked but i didn’t found the answer (and I’m pretty new to python).

The question is pretty simple. I have a list made of sublists:

ll
[[1,2,3], [4,5,6], [7,8,9]]

What I’m trying to do is to create a dictionary that has as key the first element of each sublist and as values the values of the coorresponding sublists, like:

d = {1:[2,3], 4:[5,6], 7:[8,9]}

How can I do that?

Asked By: matteo

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Source

Answer 1

you could do it this way:

ll = [[1,2,3], [4,5,6], [7,8,9]]
dct = dict( (item[0], item[1:]) for item in ll)
# or even:   dct = { item[0]: item[1:] for item in ll }
print(dct)
# {1: [2, 3], 4: [5, 6], 7: [8, 9]}

Answered By: hiro protagonist

Answer 2

Using dictionary comprehension (For Python 2.7 +) and slicing –

d = {e[0] : e[1:] for e in ll}

Demo –

>>> ll = [[1,2,3], [4,5,6], [7,8,9]]
>>> d = {e[0] : e[1:] for e in ll}
>>> d
{1: [2, 3], 4: [5, 6], 7: [8, 9]}

Answered By: Anand S Kumar

Answer 3

Using dict comprehension :

{words[0]:words[1:] for words in lst}

output:

{1: [2, 3], 4: [5, 6], 7: [8, 9]}

Answered By: The6thSense

Answer 4

Another variation on the theme:

d = {e.pop(0): e for e in ll}

Answered By: Mike Robins

Answer 5

Another:

d = {k: v for k, *v in ll}

Answered By: Kelly Bundy

Get first element of sublist as dictionary key in python

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