[Tutor] numbers and ranges

[Kent Johnson]

Kent Johnson wrote:
  Here is a solution that uses a generator to create the ranges:
> 
> def ranges(data):
>      i = iter(data)
>      first = last = i.next()
>      try:
>          while 1:
>              next = i.next()
>              if next > last+1:
>                  yield (first, last)
>                  first = last = next
>              else:
>                  last = next
>      except StopIteration:
>          yield (first, last)
> 
> print list(ranges((1,)))
> print list(ranges((1,2,3)))
> print list(ranges((1,3,5)))
> print list(ranges((1,3,5,7,8,9,10)))

I suspected when I wrote this that if I were clever enough I could use 
itertools.groupby() to solve this. It turns out that the last example at
http://docs.python.org/lib/itertools-example.html
is exactly the problem of finding runs in a sequence.

Kent