Get index value in python list comprehension (for in preceded with variable)

Question

This syntax is able to define new list above list (or array):

[v for v in ['a', 'b']]

But how to get the index of the list? This doesn't work

[k for k, v in ['a', 'b']]

Expected output

[0, 1]

Answer 1

Probably you have meant indexes, as there are no keys in list. We can get them like this:

indexes = [index for index,element in enumerate(your_list)]

But this isn't really necessary, we can get length of the list and get indexes from it as indexes are from 0 to [length of list]-1:

length = len(your_list)
indexes = list(range(length))

Answer 2

[idx for idx, val in enumerate(['a', 'b'])]

output

[0, 1]

Answer 3

enumerated_list = [(index, value) for index, value in enumerate(['a', 'b'])]
print(enumerated_list)

output: [(0, 'a'), (1, 'b')]

Answer 4

I think you meant index. Remember that lists have no keys, those are dictionaries.

[index for index, value in enumerate(['a', 'b'])]

The enumerate function is basically range but it returns the index and the value.

Read more on enumerate here.

Answer 5

You can use range():

range(len(['a', 'b']))

range() will return a sequence. If you need a list specifically, you can do

list(range(len(['a', 'b'])))

As mentioned in the comments, in python lists do not have keys.