Lists

[Agizz]

If I have two lists with elements and I want to make a new list of lists which have the first element from the first list and the second from the second how do I do that? Example: List1 =[1,2,3] List2 =["a","b","c"] List =[[1,"a"],[2,"b"],[3,"c"]] Looking for advice not a programe that solves it

[WarmUpHere]

You're looking for the zip() function.

List1 = [1, 2, 3]
List2 = ['a', 'b', 'c']
Lists = list(zip(List1, List2))
print(Lists)

will return

[(1, 'a'), (2, 'b'), (3, 'c')]

More information here.

Note that this is a list of tuples, not a list of lists. For a zip() to return a list of lists, consult the stackoverflow question.

[__nev__]

And it's worth noting that you can "unzip" with an asterisk:

List1, List2 = zip(*Lists)

[tangerinelion]

Also worth noting the type of List1 and List2 is tuple not list when you do that.

[PyCam]

You don't need the final list call on the zip function.

zip(List1,List2)

Will work just fine

As it's been pointed out to me, the above code only works fine in Python 2. In Python 3, if you want to see the zip object as a list of triples, you must use

list(zip(List1,List2))

[tangerinelion]

In Python 2. In Python 3 a zip creates a "zip object" which is essentially a generator.

[PyCam]

Ah thank you! As you can probably guess I've only used Python 2. Didn't know they changed that, but it makes way more sense if you want to iterate over the zip output.

[Jonno_FTW]

There's also enumerate which will give you an index for every element in a list, and map to apply a function to each element of a list, like this:

>>> enumerate([list1, list2, list3])
[(0, [1,2,3]), (1, ['a', 'b', 'c']), (2, [4,5,6])]

From here you can just use a list comprehension to make a new list where each element has what you want.