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Re: extract points of acircle [message #93560 is a reply to message #93559]

Thu, 18 August 2016 10:46

wlandsman
Messages: 743
Registered: June 2000

Senior Member

Its not the most efficient way, but I would use the program dist_circle.pro
http://idlastro.gsfc.nasa.gov/ftp/pro/image/dist_circle.pro

dist_circle, dim, N, xcenter, ycenter
g = where( dim lt radius)

where N is the dimension of the square array. g will give the 1-d index of every pixel within the specified radius. You can use ARRAY_INDICES() to convert this 1d index into separate X and Y subscript values. --Wayne

On Thursday, August 18, 2016 at 10:30:18 AM UTC-4, AGW wrote:
> On Tuesday, August 16, 2016 at 5:21:20 PM UTC+2, AGW wrote:
>> Hi,
>> I want to plot four circles on picture then extract mean x,y for every circle
>> I use this program.
>>
>> ;******************************************
>> FUNCTION CIRCLE, xcenter, ycenter, radius
>> points = (2 * !PI / 99.0) * FINDGEN(100)
>> x = xcenter + radius * COS(points )
>> y = ycenter + radius * SIN(points )
>> RETURN, TRANSPOSE([[x],[y]])
>> END
>>
>> restore,file='sm.isv' ;/v
>> sm1=sm[*,*,5]
>> window,0,xs=999,ys=512
>> tvscl,sm1
>>
>> n=5
>> for i=0,n-1 do begin
>> radius=10*i
>> pp=circle(200,352,radius)
>> cgPlotS, pp,color='red',thick=2.0, /Device
>>
>> ;*************************************
>>
>> at this point no problem, I want to print mean(x,y) for every circle
>>
>> how can I do it ?
>>
>> help, please
>
> every point in circle have a coordinates x,y, I want to extract this coordinates for every circle

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[Message index]

		extract points of acircle By: Ali Gamal on Tue, 16 August 2016 08:21
		Re: extract points of acircle By: Craig Markwardt on Wed, 17 August 2016 09:06
		Re: extract points of acircle By: Ali Gamal on Thu, 18 August 2016 07:30
		Re: extract points of acircle By: wlandsman on Thu, 18 August 2016 10:46
		Re: extract points of acircle By: Ali Gamal on Thu, 18 August 2016 12:33

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