How to increase the speed of this program?

[Leo Kislov]

Peter Otten wrote:
> Peter Otten wrote:
>
> > HYRY wrote:
> >
> >> I want to join two mono wave file to a stereo wave file by only using
> >> the default python module.
> >> Here is my program, but it is much slower than the C version, so how
> >> can I increase the speed?
> >> I think the problem is at line #1, #2, #3.
> >
> >> oarray = array.array("h", [0]*(len(larray)+len(rarray))) #1
> >
> > ITEMSIZE = 2
> > size = ITEMSIZE*(len(larray) + len(rarray))
> > oarray = array.array("h")
> > oarray.fromstring("\0" * size)
> >
> > may be a bit faster.
>
> Confirmed:
>
> $ python2.5 -m timeit -s'from array import array; N = 10**6' 'a =
> array("h"); a.fromstring("\0"*(2*N))'
> 100 loops, best of 3: 9.68 msec per loop
> $ python2.5 -m timeit -s'from array import array; N = 10**6' 'a = array("h",
> [0]*N);'
> 10 loops, best of 3: 199 msec per loop

Funny thing is that using huge temporary string is faster that
multiplying small array:

C:\Python25>python -m timeit -s"from array import array; N = 10**6" "a
=array('h'); a.fromstring('\0'*(2*N))"
100 loops, best of 3: 9.57 msec per loop

C:\Python25>python -m timeit -s"from array import array; N = 10**6" "a
= array('h','\0\0'); a*N"
10 loops, best of 3: 28.4 msec per loop

Perhaps if array multiplication was as smart as string multiplication
then array multiplication version would be the fastest.

  -- Leo