how many nested for can we utilize?

[Reedick, Andrew]

> -----Original Message-----
> From: python-list-bounces+jr9445=att.com at python.org [mailto:python-
> list-bounces+jr9445=att.com at python.org] On Behalf Of Lie
> Sent: Monday, August 18, 2008 11:04 AM
> To: python-list at python.org
> Subject: Re: how many nested for can we utilize?
> 
> On Aug 17, 4:23 pm, Fredrik Lundh <fred... at pythonware.com> wrote:
> > Patrol Sun wrote:
> > > when I use 20 for ,"SystemError: too many statically nested blocks"
> > > When I use 100 for ,"IndentationError: too many levels of
> indentation"
> > > How to handle these errors?
> >
> > so why exactly are you trying to nest 20 or 100 for-in loops?
> >
> > </F>
> 
> I think most (all?) algorithm that might use 20+ levels of for-in
> loops could almost always be replaced with a recursive function. Or at
> least they could be broken into smaller functions.


Recursion is slow.  There was a thread on permutations and I ran some timings on various methods of nesting loops.  Also, I do remember hitting nested for limits very quickly.  I think list comprehensions allowed for deeper nesting than straight for loops.  Anyway, the thread contains various code and solutions that should help the OP.

http://mail.python.org/pipermail/python-list/2008-January/473787.html

Cookbook is relatively decent.  5 deep, 100 iterations:
	list comprehension:  11.02
	nested for loop   :  13.16   +19%
	cookbook          :  18.85   +71%
	recursion         :  69.00  +526%
	eval              :  13.30   +20%


Start of thread:  http://mail.python.org/pipermail/python-list/2008-January/473650.html



*****

The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential, proprietary, and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from all computers. GA623