python - List comprehension list of lists

Question

I have a list of lists, and would like to use list comprehension to apply a function to each element in the list of lists, but when I do this, I end up with one long list rather than my list of lists.

So, I have

x = [[1,2,3],[4,5,6],[7,8,9]]
[number+1 for group in x for number in group]
[2, 3, 4, 5, 6, 7, 8, 9, 10]

But I want to get

[[2, 3, 4], [5, 6, 7], [8, 9, 10]]

How do I go about doing this?

Answer 1

Use this:

[[number+1 for number in group] for group in x]

Or use this if you know map:

[map(lambda x:x+1 ,group) for group in x]