IntSpan?

[Chris Liechti]

"Jeff Bienstadt" <jeffbi at jetsoft.com> wrote in
news:3c9a1ae9$1 at news.nwlink.com: 
> "Neal Norwitz" <neal at metaslash.com> wrote in message
> news:3C99F049.5A78B149 at metaslash.com...
>> Jeff Bienstadt wrote:
>> > I'm looking for something that inteligently handles and 
manipulates
>> > spans of integers, such as: 2-356,456,458-500
>>
>> I'm not familiar with IntSpan, but have you looked at the builtin
>> range()? 
>> >>> print range.__doc__
>> range([start,] stop[, step]) -> list of integers
>>
> Yes, I knew about range, but that's not quite what I'm looking for.
> 
> Using range to create the full list of integers seems prohibitively
> expensive --- spans in the range 1-400000 are not at all out of 
> line.
> 
...
> I can see from your reply how range could be useful in the
> implementation, for creating temporary lists of values to work
> with but again, since the spans could be quite long, this
> seems expensive.

in ypthon 2.2 you could do that with a generator.
>>> form __future__ import generators
>>> def spanning():
...    	for i in xrange(3,10):
...    	    	yield i
...    	yield 99
...    	for i in xrange(20,30):
...    	    	yield i

testing:
>>> for i in spanning(): print i

using xrange instead of range does not allocate a list but generates 
the vaulues when they're needed.

chris

-- 
Chris <cliechti at gmx.net>