Convert list of tuples to list?

Question

How do I convert

[(1,), (2,), (3,)]

to

[1, 2, 3]

Answer 1

>>> a = [(1,), (2,), (3,)]
>>> b = map(lambda x: x[0], a)
>>> b
[1, 2, 3]

With python3, you have to put the list(..) function to the output of map(..), i.e.

b = list(map(lambda x: x[0], a))

This is the best solution in one line using python built-in functions.