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Re: a newbie question on code efficiency [message #26298 is a reply to message #26297]

Fri, 17 August 2001 20:47

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

GB Smith (gogosgogos@usa.net) writes:

> i have a little challenge for you which i stumbled into..
> i tried to write a program which takes a 3d array,
> sets a cutoff at a certain level and then creates a mask
> of all values above that level. the mask has to be 1 and 0.
> i came up with this code, but could never get rid of the loop.
>
> any suggestions on how to get rid of the loop?
> i would prefer array operators for speed :)
>
> ;----------------------------------------------------------- ------
>
> PRO MAKE_MASK
>
> a = dialog_pickfile()
> b = READ_BINARY(a, DATA_TYPE=1, DATA_DIMS=[160,256,256])
>
> b_dims = size(b)
> x_dim = b_dims[1]
> y_dim = b_dims[2]
> z_dim = b_dims[3]
>
> cutoff = 180
>
>
> e = b
>
> for i = 0, (x_dim-1) do begin
> for j = 0, (y_dim-1) do begin
> for k = 0, (z_dim-1) do begin
>
> if e[i,j,k] lt cutoff then e[i,j,k]=0
> if e[i,j,k] ge cutoff then e[i,j,k]=1
>
> endfor
> endfor
> endfor
>
> ; and so on to use the mask further in the program
>
>
> END

My goodness, an array operator question even I
can handle! :-)

e = b GE cutoff

Cheers,

David
--

---
David W. Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438, E-mail: david@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: a newbie question on code efficiency By: Dominic R. Scales on Mon, 20 August 2001 11:06
		Re: a newbie question on code efficiency By: David Fanning on Sat, 18 August 2001 12:26
		Re: a newbie question on code efficiency By: gogosgogos on Sat, 18 August 2001 11:31
		Re: a newbie question on code efficiency By: David Fanning on Sat, 18 August 2001 06:41
		Re: a newbie question on code efficiency By: Dominic R. Scales on Sat, 18 August 2001 05:44
		Re: a newbie question on code efficiency By: David Fanning on Sat, 18 August 2001 05:22
		Re: a newbie question on code efficiency By: Dominic R. Scales on Sat, 18 August 2001 04:10
		Re: a newbie question on code efficiency By: gogosgogos on Sat, 18 August 2001 03:13
		Re: a newbie question on code efficiency By: David Fanning on Fri, 17 August 2001 20:47
		Re: a newbie question on code efficiency By: R.Bauer on Sun, 09 September 2001 11:48

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