R: [Gdal-dev] trivial (?) optimization for gdal.i:GDALReadRaster( )

[Alessandro Amici]

> > [...] however, to
> > the best of my  knowledge there isn't any reason these couldn't both be
> > supported is there?
>
> in principle no.
> in practice i can easily see the maintainace cost to climb quite high.

it actually depends on how you do it. if you only want configure time choice 
between Numeric and numarray you mostly have to s/Numeric/numarray/g inside 
pymod.

a first try at a zero-copy implementation with numarray gave me (same program 
as before) the quite amazing numbers below:

real    0m16.031s
user    0m11.249s
sys     0m4.462s

CPU: CPU with timer interrupt, speed 1000.15 MHz (estimated)
Profiling through timer interrupt
vma      samples  %           app name                 symbol name
001323b0 8026     49.8355     libgdal.so.1.1.9         GDALCopyWords
c01b0310 2180     13.5362     vmlinux                  __copy_to_user_ll
00077990 1583      9.8292     libc-2.3.2.so            memcpy
c01afdf0 1322      8.2086     vmlinux                  fast_clear_page
001322d0 849       5.2717     libgdal.so.1.1.9         GDALSwapWords
00000000 304       1.8876     python2.3                (no symbols)

which means that the overhead of using python instead of C for reading a 500Mb 
image with gdal wuold be a bare 2% of cpu time!

IMHO looking at numarray is definetly worth.

cheers,
alessandro