On 13/09/17 13:24, Kátia Emidio wrote:

> Dear Rolf,

>

> Thanks for your help!

>

> What I need is a spatial window with shape equal to the figure attached.

> This figure I made using ArcGis, but it is important to me make it in R.

> After having this figure I will make some analysis using spatstat among

> others. The points within figure are trees...

(1) I believe that this discussion should be kept on-list. It is not my

role to provide private consulting for you. I am therefore cc-ing the

list in this email.

(2) It is still not completely clear what you really want; the figure

that you attached appears to be a disc with 4 diameters superimposed.

So you might be after a single (circular) owin object and a line segment

pattern consisting of the 4 diameters. Or you might be after *eight*

owin objects, each being one the eight disc-segments into which the

diameters divide the disc.

I shall assume the latter. To start with define a function, say "wedge":

wedge <- function(theta1,theta2,radius,npoly=100,centre=c(0,0)){

library(spatstat)

# Should do some checking on the values of theta1 and theta2 here,

# but I shan't bother.

theta <- seq(theta1,theta2,length=npoly+1)

x <- c(0,radius*cos(theta),0)

y <- c(0,radius*sin(theta),0)

W <- owin(poly=list(x=x,y=y))

return(affine(W,vec=centre))

}

Then do something like:

wedgies <- vector("list",length=8)

cntr <- c(673593.21,673593.21)

for(i in 1:8) wedgies[[i]] <- wedge((i-1)*pi/4,i*pi/4,15,centre=cntr)

ttt <- tess(tiles=wedgies)

plot(ttt) # Looks OK to me.

And maybe also do:

W <- do.call(union.owin,wedgies)

plot(W)

for(i in 1:8) {

plot(wedgies[[i]],add=TRUE,border="red")

readline("Go? ")

}

Also looks OK to me.

Is *this* what you want?

cheers,

Rolf Turner

--

Technical Editor ANZJS

Department of Statistics

University of Auckland

Phone: +64-9-373-7599 ext. 88276

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