Dict Comprehension python from list of lists

Question

I have a list of lists and I am trying to make a dictionary from the lists. I know how to do it using this method. Creating a dictionary with list of lists in Python

What I am trying to do is build the list using the elements in the first list as the keys and the rest of the items with the same index would be the list of values. But I can't figure out where to start. Each list is the same length but the length of the lists vary

exampleList = [['first','second','third'],['A','B','C'], ['1','2','3']]

resultDict = {'first':['A','1'],'second':['B','2'],'third':['C','3']}

bhansa · Answer 1 · 2017-10-06T19:18:30.760

3

Unpack the values using zip(*exampleList) and create a dictionary using key value pair.

dicta = {k:[a, b] for k, a, b in zip(*exampleList)}
print(dicta)
# {'first': ['A', '1'], 'second': ['B', '2'], 'third': ['C', '3']}

If more lists:

dicta = {k:[*a] for k, *a in zip(*exampleList)}
# {'first': ['A', '1', 4], 'second': ['B', '2', 5], 'third': ['C', '3', 6]}

edited Oct 06 '17 at 19:18

answered Oct 06 '17 at 19:00

bhansa

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score 3 · Answer 2 · answered Oct 06 '17 at 19:01

3

Unpacking and using zip followed by a dict comprehension to get the mapping with first elements seems readable.

result_dict = {first: rest for first, *rest in zip(*exampleList)}

answered Oct 06 '17 at 19:01

miradulo

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score 1 · Answer 3 · answered Oct 06 '17 at 18:59

If you don't care about lists vs tuples, it's as simple as using zip twice:

result_dict = dict(zip(example_list[0], zip(*example_list[1:])))

Otherwise, you'll need to through in a call to map:

result_dict = dict(zip(example_list[0], map(list, zip(*example_list[1:]))))

score 1 · Accepted Answer · answered Oct 06 '17 at 19:05

1

Take care of the case when exampleList could be of any length..

exampleList = [['first','second','third'],['A','B','C'], ['1','2','3'],[4,5,6]]

z=list(zip(*exampleList[1:]))
d={k:list(z[i])  for i,k in enumerate(exampleList[0])}
print(d)

output

{'first': ['A', '1', 4], 'second': ['B', '2', 5], 'third': ['C', '3', 6]}

answered Oct 06 '17 at 19:05

kaza

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I just added that to the description because the length of the lists can vary. – mickNeill Oct 06 '17 at 19:14

score 0 · Answer 5 · answered Oct 06 '17 at 18:59

0

The zip function might be what you are looking for.

exampleList = [['first','second','third'],['A','B','C'], ['1','2','3']]
d = {x: [y, z] for x, y, z in zip(*exampleList)}
print(d)
#{'first': ['A', '1'], 'second': ['B', '2'], 'third': ['C', '3']}

answered Oct 06 '17 at 18:59

Arthur Gouveia

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Dict Comprehension python from list of lists

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