Python and STL efficiency

[Pebblestone]

Here's the result:

What do you know
fool
chicken crosses road
f elapsed: 1.260000 seconds
f2 elapsed 2.110000 seconds



bearophileHUGS at lycos.com wrote:
> Pebblestone:
> > (defun test4 ()
> >   (let ((a (make-array 4000000 :element-type 'string
> > 					   :adjustable nil))
> > 		(b nil))
> > 	(dotimes (i 1000000)
> > 	  (progn
> > 		(let ((j (1- (* 4 i))))
> > 		  (setf (aref a (incf j)) "What do you know")
> > 		  (setf (aref a (incf j)) "so long ...")
> > 		  (setf (aref a (incf j)) "chicken crosses road")
> > 		  (setf (aref a (incf j)) "fool"))))
> > 	(setf b (remove-duplicates a))
> > 	(map 'vector #'print b)))
>
>
> That test4 function can be compared to this one, with explicit
> preallocation (and xrange instead of range!):
>
> def f2():
>     n = 1000000
>     a = [None] * n * 4
>     for i in xrange(0, n*4, 4):
>         a[i] = 'What do you know'
>         a[i+1] = 'so long...'
>         a[i+2] = 'chicken crosses road'
>         a[i+3] = 'fool'
>     for s in set(a):
>         print s
>
> But note this a list (that is an array, a list is a different data
> structure) of python becomes filled with pointers. I don't know what
> your CL does exactly.
>
> I can also suggest you to use Psyco too here
> (http://psyco.sourceforge.net/):
>
> import psyco
> psyco.bind(f2)
>
> It makes that f2 more than twice faster here.
> 
> Bye,
> bearophile