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Re: [Q] Reading from file, speed [message #18912 is a reply to message #18911]

Thu, 10 February 2000 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

Koen Janssens (janssens@ifu.bepr.ethz.ch) writes:

> I am looking for a better way to import data into IDL, the one I am
> using now seems very slow (about 20 secs for reading in 2 MBytes). Here
> is the script that I use:
>
> openr, ms_dat_unit, ms_dat_file
> ms = bytarr(dimx,dimy,dimz)
> for z = 0,(dimz-1) do begin
> for y = 0,(dimy-1) do begin
> for x = 0,(dimx-1) do begin
> readu, ms_dat_unit, tmp
> ms[x,y,z] = tmp
> endfor
> endfor
> endfor
> close, ms_dat_unit
> free_lun, ms_dat_unit
>
> The file I am reading contains integers in binary format (volume data
> 128^3).

IDL is sometimes considered a loopy language, but
it is definitely NOT a looping language. :-)

Those FOR loops are killing you. Try something
like this:

openr, ms_dat_unit, ms_dat_file, /get_lun
ms = bytarr(dimx,dimy,dimz)
readu, ms_dat_unit, ms
free_lun, ms_dat_unit

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		Re: [Q] Reading from file, speed By: Koen Janssens on Thu, 10 February 2000 00:00
		Re: [Q] Reading from file, speed By: davidf on Thu, 10 February 2000 00:00
		Re: [Q] Reading from file, speed By: Ivan Zimine on Thu, 10 February 2000 00:00

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