On May 9, 4:09 pm, Paul Hankin <[EMAIL PROTECTED]> wrote:
> On May 9, 10:10 am, [EMAIL PROTECTED] wrote:
>
> > Hello all,
>
> > I have a dictionary of which i'm itervalues'ing through, and i'll be
> > performing some logic on a particular iteration when a condition is
> > met with trusty .startswith('foo'). I need to grab the previous
> > iteration if this condition is met. I can do something with an extra
> > var to hold every iteration while iterating, but this is hacky and not
> > elegant.
>
> Often when you're iterating, 'hacky' code can be lifted out into a
> separate generator, keeping the details of the hacks nicely away from
> your code. That's true here...
>
> def iterprevious(seq):
> """Generate pairs of (previous element, current element)
> from seq."""
> last = None
> for x in iter(seq):
> yield last, x
> last = x
>
> Then, when you want use it...
>
> for previous, (key, value) in iterprevious(d.iteritems()):
> ... In the loop, previous will either be None if we're on the
> first element, otherwise (previous_key, previous_value).
>
> --
> Paul Hankin
Hi all - some good stuff here. Thanks for the info, I have a few
ideas
to play with.
thanks again
dan.
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