On 09/07/11 18:22, Laurent wrote:
Anyway I was just asking if there is something better than
enumerate. So the answer is no? The fact that I have to create
a tuple with an incrementing integer for something as simple
as checking that I'm at the head just sounds awfully
unpythonic to me.
I've made various generators that are roughly (modulo
edge-condition & error checking) something like
def with_prev(it):
prev = None
for i in it:
yield prev, i
i = prev
def with_next(it):
prev = it.next()
for i in it:
yield prev, i
prev = i
yield prev, None
which can then be used something like your original
for cur, next in with_next(iterable):
if next is None:
do_something_with_last(cur)
else:
do_regular_stuff_with_non_last(cur)
for prev, cur in with_prev(iterable):
if prev is None:
do_something_with_first(cur)
else:
do_something_with_others(cur)
If your iterable can return None, you could create a custom
object to signal the non-condition:
NO_ITEM = object()
and then use NO_ITEM in place of "None" in the above code.
-tkc
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