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Re: circles [message #9500]

Fri, 11 July 1997 00:00

Kevin Reardon
Messages: 2
Registered: July 1995

Junior Member

lady of the elves wrote:
>
> I would really like to have a circularly-filled array; if anyone has
> better knowledge, please let me know :)
> Thanks.

The most direct way get an array of distances from some central point in IDL is:

;for a circle centered at (150,50)
xx = rebin(findgen(201,201) - 150,201,201)
yy = rebin(findgen(1,201) - 50,201,201)

radial_distance = sqrt(xx^2 - yy^2)

tvscl,radial_distance le 50 ; displays a white filled circular mask

The previous suggestion by Peter Suetterlin (pit@uni-sw.gwdg.de) of:
img = (shift(dist(X,Y),x0,y0)) LT R
doesn't seem to work if x0 and y0 are not equal to X/2 and Y/2 (i.e. the
circle is not centerted) because of wrapping problems when the array is shifted.

kevin
kreardon@na.astro.it

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[Message index]

		Re: circles By: Kevin Reardon on Fri, 11 July 1997 00:00
		Re: circles By: pit on Thu, 10 July 1997 00:00
		Re: circles By: Joseph M Zawodny on Thu, 10 July 1997 00:00
		Re: circles By: Martin Lizak (NEI) on Wed, 09 July 1997 00:00
		Re: circles By: David Foster on Wed, 09 July 1997 00:00

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