[R-sig-Geo] ppp unique point coordinates?
r.turner at auckland.ac.nz
Thu Apr 7 13:38:09 CEST 2011
The ppp() function simply gives you a ***warning*** if there are duplicated
points; duplications are permitted.
However you should be careful.
The theory on which most point process theory rests assumes that the
processes are ***simple***, so there can be no duplicated points. Hence
any methodology that invokes the usual theory will be invalid for your
If you are not invoking any such methodology, then go for it.
If you don't like getting the warnings, then you could use
On 07/04/11 23:27, francesco wrote:
> Hi everyone, I am trying to process a lot of points as ppp points, put I
> see that the ppp object cannot be created if the coordinate matrix has
> duplicated values. I have duplicates because the points are acutally
> from a 3D laser scan survey so I will need duplicats. My code to figure
> my error was:
> pts is the x,y matrix and i is the slice that I used to check when my
> error occured.
> ppp(pts[1:i,1], pts[1:i,2], range(pts[1:i,1]), range(pts[1:i,2]))
> Question is: is there a way to overcome this? My final objective is
> "simply" to use pixellate to aggregate statistics locally (ie average
> point density in a square meter grid or mean reflectance value of each
> Cheers, and thanks for your time.
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