How do I combine two lists into a dictionary in Python? [duplicate]

Question

I have two lists of the same length:

[1,2,3,4] and [a,b,c,d]

I want to create a dictionary where I have {1:a, 2:b, 3:c, 4:d}

What's the best way to do this?

Answer 1

dict(zip([1,2,3,4], [a,b,c,d])) 

If the lists are big you should use itertools.izip.

If you have more keys than values, and you want to fill in values for the extra keys, you can use itertools.izip_longest.

Here, a, b, c, and d are variables -- it will work fine (so long as they are defined), but you probably meant ['a','b','c','d'] if you want them as strings.

zip takes the first item from each iterable and makes a tuple, then the second item from each, etc. etc.

dict can take an iterable of iterables, where each inner iterable has two items -- it then uses the first as the key and the second as the value for each item.

Answer 2

>>> dict(zip([1, 2, 3, 4], ['a', 'b', 'c', 'd'])) {1: 'a', 2: 'b', 3: 'c', 4: 'd'} 

If they are not the same size, zip will truncate the longer one.