query x,y coordinates inside/outside bounding ellipsoid
I have the x,y co-ordinates for a bounding ellipsoid in a data.frame. And then I have several query
x,y co-ordinates in a data.fame. The x,y co-ordinates for a bounding ellipsoid was calculated using the function...
exy <- ellipsoidhull(X[,1:2])
such that....
plot(predict(exy), xlim=c(-0.018, 0.015), ylim=c(-0.018,0.015),
cex=0.1, type="l")
gives me a plot like this....
开发者_JS百科I have query like this....
V2 V3
-0.0167 -0.0137
-0.0159 -0.0127
-0.0150 -0.0127
-0.0164 -0.0137
-0.0164 -0.0134
-0.0173 -0.0131
How can I find which of the query
is within/outside the bounding ellipsoid? Is there an R function to do this? Thanks
Package mgcv
offers such function (but is not the only one - if you care to learn about spatial objects, see, for example, sp::overlay
). This is example from the in.out()
function.
library(mgcv)
data(columb.polys)
bnd <- columb.polys[[2]]
plot(bnd,type="n")
polygon(bnd)
x <- seq(7.9,8.7,length=20)
y <- seq(13.7,14.3,length=20)
gr <- as.matrix(expand.grid(x,y))
inside <- in.out(bnd,gr)
points(gr,pch=as.numeric(inside)+1)
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