| Re: Maximum Intensity without FOR Loop [message #39402] |
Tue, 11 May 2004 12:46 |
btt
Messages: 345
Registered: December 2000
|
Senior Member |
|
|
Stefan Tuchschmid wrote:
> Hi there
> a lot of posts talk about the necessity to avoid FOR loops ('if you
> use for loops, make sure a lot of stuff is happening in there...').
> However, I can't seem to find a better & working solution for the
> following code fragment:
>
> FOR i=0,x_resolution-1 DO BEGIN
> FOR j=0,y_resolution-1 DO BEGIN
> reformat_data[i,j,k]=MAX(data[i,j,lower_limit:upper_limit])
> ENDFOR
> ENDFOR
>
> Background: data is a image stack (MRI 3D Data), we would like to find
> the MIP (Maximum Intesity Projection) over a certain number of images.
Hi,
IDL> data = Bindgen(3,4,5)
You could use the DIMENSION keyword to MAX to find the maximum in that
dimension (across the entire array.)
IDL> print, max(data, dim = 3)
48 49 50
51 52 53
54 55 56
57 58 59
Or, you could find the maximum using the 'max' operator on specified
dismension (you can do more than two at a time.)
IDL> print, data[*,*,0] > data[*,*,2]
24 25 26
27 28 29
30 31 32
33 34 35
Ben
|
|
|
|
| Re: Maximum Intensity without FOR Loop [message #39403 is a reply to message #39402] |
Tue, 11 May 2004 12:29  |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
Stefan Tuchschmid writes:
> Hi there
> a lot of posts talk about the necessity to avoid FOR loops ('if you
> use for loops, make sure a lot of stuff is happening in there...').
> However, I can't seem to find a better & working solution for the
> following code fragment:
>
> FOR i=0,x_resolution-1 DO BEGIN
> FOR j=0,y_resolution-1 DO BEGIN
> reformat_data[i,j,k]=MAX(data[i,j,lower_limit:upper_limit])
> ENDFOR
> ENDFOR
>
> Background: data is a image stack (MRI 3D Data), we would like to find
> the MIP (Maximum Intesity Projection) over a certain number of images.
> The currrent solution is too slow, and a better solution highly
> appreciated!
> Algorithm-Freaks? Anyone?
I should think something like this would work:
mip = Max(data[*,*,lower_limit:upper_limit], Dimension=3)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Coyote's Guide to IDL Programming: http://www.dfanning.com/
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
