Threading/map question

[Anand]

Michael Hudson <mwh at python.net> wrote in message news:<m24r9szcx0.fsf at localhost.bris.ac.uk>...
> anandpillai6 at yahoo.com (Anand) writes:
> 
> > A question about function performance.
> > 
> > I have a list of integers on which an operation is to be performed,
> > say an addition or subtraction. Since the list is huge (len >= 100000)
> > ,I can do it in two ways (I thought)
> 
> OK.
> 
> >  I found that the thread solution takes lesser time than the map
> > solution. Can this be a general approach for all data structures in python
> > or does it apply only to lists.
> 
> Asking if threading or map gives better performance seems to me like
> asking whether mashed potatoes or tofu are better at keeping one dry.


  Thank You. 
> 
> However, 
> 
>     ldataout = [None]*len(ldatain)
>     for i in range(len(ldatain)):
>         ldataout[i] = 255 - ldatain[i]
> 
> is likely to be quicker than
> 
>     ldataout = map(lambda x: 255 - x, ldatain)
> 
> because you don't have to take a trip through the function call
> machinery for each element of the list in the first case.
> 

  Guess I will stick with using mashed potatoes :-)
  I found a combination of mashed potatoes and tofu to be 
  faster than using mashed potatoes / tofu by themselves or standing
  in the rain.

> Cheers,
> M.


Thanks
Anand