On 30/10/2013 13:08, Peter O'Doherty wrote: > Hi List, > > I know a geometric sequence can be produced by: > > series = [2**x for x in range(7)] > > But I would like to curtail the sequence before the last element excedes > a certain value. Is there a better way of doing it that the following: > > for x in range(20): > series_element = 2**x > print series_element > if series_element > 60: > break > print series >
Change from range to xrange, if you want this to be generally more efficient. Doesn't matter for small numbers like this, but I assume you're asking about a potentially much larger value and/or a much larger multiplier. If you're going to print them, and not build a list, then the while loop is certainly "better" than the comprehension. On the other hand, if you need the list (as you do in your first example), then the comprehension with a conditional is probably clearer. And then if performance becomes an issue, you can figure an upper bound (which in this case is trivial using logs), and just make sure the xrange is just large enough to exceed the value you want. Finally, if you really want efficiency, then apply some algebra to the problem, and don't loop at all. -- DaveA _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
