obtaining multiple values from a function.

Carsten Haese carsten at uniqsys.com
Tue Sep 25 12:01:29 CEST 2007


On Tue, 2007-09-25 at 10:41 +0100, Paul Rudin wrote:
> Going off on a tangent a bit, but I was idly considering the absence
> of itertools.ireduce the other day. A problem is that reduce gives a
> single result, so it's not clear what ireduce would do (perhaps why
> it's not there). One obvious candidate would be to give the whole
> sequence of partial reductions. I'm not sure if this would be
> generally useful, but it would give a succinct way to do the Fibonacci
> sequence:
> 
> itertools.ireduce(operator.add, itertools.count())

Let's try it:

>>> def ireduce(op, iterable, partial=0):
...   for nxt in iterable:
...     partial = op(partial, nxt)
...     yield partial
... 
>>> import operator
>>> from itertools import islice, count
>>> 
>>> for x in islice(ireduce(operator.add, count()), 0, 10):
...   print x
... 
0
1
3
6
10
15
21
28
36
45

That's not the Fibonacci sequence.

-- 
Carsten Haese
http://informixdb.sourceforge.net





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