On Mon, 29 Oct 2012 23:40:53 +1100, Chris Angelico wrote: > On Mon, Oct 29, 2012 at 3:52 PM, Andrew Robinson > <andr...@r3dsolutions.com> wrote: >> I am curious as to how quickly it constructs the result compared to a >> slice operation. >> >> Eg: >> a[1:5] >> vs. >> [ a[i] for i in xrange[1:5] ] > > For the most part, don't concern yourself with performance. Go with > functionality and readability. In the trivial case shown here, the slice > is WAY clearer, so it should definitely be the one used; in other cases, > the slice might simply be insufficient, so you go with whatever achieves > your goal. Performance will usually be "good enough", even if there's a > marginally faster way.
Slicing is about an order of magnitude faster: [steve@ando ~]$ python2.7 -m timeit -s "x = range(100, 1000, 2)" "x [20:40]" 1000000 loops, best of 3: 0.342 usec per loop [steve@ando ~]$ python2.7 -m timeit -s "x = range(100, 1000, 2)" "[x[i] for i in xrange(20, 40)]" 100000 loops, best of 3: 3.43 usec per loop -- Steven -- http://mail.python.org/mailman/listinfo/python-list
