Creating a Python list from a list of tuples

Question

If I have, for example, a list of tuples such as

a = [(1,2)] * 4

how would I create a list of the first element of each tuple? That is,

Answer 1

I recently found out about Python's zip() function. Another way to do what I want to do here is:

list( zip( *a )[0] )

tup_list = zip( list1, list2 ) interleaves two lists into a list of 2-tuples, but zip( *tup_list ) does the opposite, resulting in a list of a tuple of list1 and a tuple of list2.