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Re: Help requested in eradicating FOR loops [message #57711 is a reply to message #57538]

Tue, 18 December 2007 03:00

dplatten
Messages: 32
Registered: December 2007

Member

> Off the top of my head:
> 1-reform the points to match the size of the image: x1 =
> reform(x1,image_height,image_width)
> 2-make in "index" array: idx = findgen(image_height,image_width)
> 3-make x-index and y-index arrays: x = idx mod image_height & y = idx/
> image_height (or maybe those should be image_width?)
> 4-do the calculation: distance = ( (y1-y2)*x + (x2-x1)*y + (x1*y2-
> x2*y1) ) / SQRT( (x2-x1)^2 + (y2-y1)^2 )
> 5-put together the results matrix: results =
> [[reform(image,image_height*image_width)],[distance]] (I'd have to
> check the brackets, I always do)

Thanks for the reply - as I understand it I need to make an array to
hold x pixel positions and one to hold y pixel positions. For a 4 x 6
array they would look like this:

x locations: [0,1,2,3, 0,1,2,3, 0,1,2,3, 0,1,2,3, 0,1,2,3, 0,1,2,3]
y locations: [0,0,0,0, 1,1,1,1, 2,2,2,2, 3,3,3,3, 4,4,4,4, 5,5,5,5]

I can make the x array by doing this:

test_image = findgen(4, 6) ; a dummy test "image"
temp = findgen(4 * 6)
x_locations = temp mod 4

but I am having problems creating the y locations array. Some help
would be appreciated.

Thanks, David

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[Message index]

		Re: Help requested in eradicating FOR loops By: Vince Hradil on Fri, 14 December 2007 08:24
		Re: Help requested in eradicating FOR loops By: dplatten on Tue, 18 December 2007 03:00

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