On 2006-11-28, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > I have a list of numbers and I want to build another list with every > second element multiplied by -1. > > input = [1,2,3,4,5,6] > wanted = [1,-2,3,-4,5,-6] > > I can implement it like this: > > input = range(3,12) > wanted = [] > for (i,v) in enumerate(input): > if i%2 == 0: > wanted.append(v) > else: > wanted.append(-v) > > But is there any other better way to do this.
Wether this is better, I'll leave that for others to decide. But this is a possibility: wanted = [ (1 - 2*(i%2)) * item for i, item in enumerate(input)] -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
