Select cells inside a defined window of a gridded dataset

Description

Selection of cells (or sites) around a focal cell. Cells must have have xy coordinates. Users should define a 'radius' from the focal cell that will define the window

Usage

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select.window(xf, yf, radius = 1, xydata)

Arguments

xf

The x-coordinate of the focal cell.

yf

The y-coordinate of the focal cell.

radius

The radius that define the window to select neighbor cells.

xydata

A matrix-like object. The first and second columns of data must have x and y coordinates, respectively. The remaining columns must contain species or other atributes to be selected.

Details

The function is intended to be used in gridded data, but should work on sites irregularly scattered in the xy-space.

Value

A matrix-like object in which the first and second columns are the x and y coordinates. The remaining columns includes species (or attributes) observed in the selected cells.

Author(s)

Adriano Sanches Melo

Examples

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x<-rep(1:5,each=5)
y<-rep(1:5,5)
spp<-matrix(1:100,25,4)
colnames(spp)<-c("sp1","sp2","sp3","sp4")
xyspp<-cbind(x,y,spp)
resu<-select.window(xf=3, yf=3, radius=1.1, xydata=xyspp)
resu

plot(x,y) # maintain the plot window open.
points(resu[,1:2],col=2,cex=2 ) # cells of the selected window in red.

#A reduced number of cells will be selected for focal cells located in margins.
resu<-select.window(xf=5, yf=5, radius=1.1, xydata=xyspp)
plot(x,y) # maintain the plot window open.
points(resu[,1:2],col=2,cex=2 ) # cells of the selected window in red.

# Unrecorded species in the selected window are removed from resulting dataframe (or matrix):
spp<-matrix(rep(0:1,each=50),25,4)
colnames(spp)<-c("sp1","sp2","sp3","sp4")
xyspp<-cbind(x,y,spp)
select.window(xf=3, yf=3, radius=1.1, xydata=xyspp)