mask_raster | R Documentation |
Creates a matrix or array to use as a habitat mask to account for unsuitable habitat.
mask_raster(rast, FUN, grid, crs_, prev_mask)
rast |
A raster layer created using the |
FUN |
A function that defines the criteria for suitable habitat. |
grid |
A matrix or array object of the the state-space grid. This is
returned from |
crs_ |
The UTM coordinate reference system (EPSG code) used for your location provided as an integer (e.g., 32608 for WGS 84/UTM Zone 8N). |
prev_mask |
Either |
This function creates a habitat matrix or array depending upon
whether a 2D (former) or 3D (latter) trap array is used. This matrix can be
directly included as data in Bayesian SCR models run using nimble
.
A matrix or array of 0's and 1's denoting unsuitable and suitable habitat respectively.
Daniel Eacker
mask_polygon
# simulate a single trap array with random positional noise x <- seq(-800, 800, length.out = 5) y <- seq(-800, 800, length.out = 5) traps <- as.matrix(expand.grid(x = x, y = y)) # add some random noise to locations traps <- traps + runif(prod(dim(traps)),-20,20) mysigma = 300 # simulate sigma of 300 m mycrs = 32608 # EPSG for WGS 84 / UTM zone 8N # create state-space grid and extent Grid = grid_classic(X = traps, crs_ = mycrs, buff = 3*mysigma, res = 100) # run previous code used for mask_polygon() to create raster for example library(sf) poly = st_sfc(st_polygon(x=list(matrix(c(-1665,-1665,1730,-1650,1600,1650, 0,1350,-800,1700,-1850,1000,-1665,-1665),ncol=2, byrow=TRUE))), crs = mycrs) hab_mask = mask_polygon(poly = poly, grid = Grid$grid, crs_ = mycrs, prev_mask = NULL) # create raster for demonstration purposes library(raster) rast <- raster(nrow=dim(hab_mask)[1], ncol=dim(hab_mask)[2],ext=Grid$ext, crs=mycrs) rast[] = apply(hab_mask,2,rev) # create habitat mask using raster hab_mask_r = mask_raster(rast = rast, FUN = function(x){x==1}, grid = Grid$grid, crs_ = mycrs, prev_mask = NULL) # make simple plot # returns identical results as input rast (but this was just an example raster) plot(raster(apply(hab_mask_r,2,rev))) # create an array of traps, as an approach where individuals will only be # detected at one of the trap arrays (e.g., Furnas et al. 2018) Xarray = array(NA, dim=c(nrow(traps),2,2)) Xarray[,,1]=traps Xarray[,,2]=traps+4000 # shift trapping grid to new locations # create grid and extent for 3D trap array GridX = grid_classic(X = Xarray, crs_ = mycrs, buff = 3*mysigma, res = 100) # make simple plot par(mfrow=c(1,1)) plot(GridX$grid[,,1],xlim=c(-1600,6000),ylim=c(-1600,6000),col="darkgrey", pch=20,ylab="Northing",xlab="Easting") points(Xarray[,,1],col="blue",pch=20) points(GridX$grid[,,2],pch=20,col="darkgrey") points(Xarray[,,2],col="blue",pch=20) # create polygon to use as a mask and covert to raster poly = st_sfc(st_polygon(x=list(matrix(c(-1660,-1900,5730,-1050,5470,5650, 0,6050,-1800,5700,-1660,-1900),ncol=2, byrow=TRUE))), crs = mycrs) # add polygon to plot plot(poly, add=TRUE) # make raster from polygon rast = raster(xmn=-2000, xmx=6000, ymn=-2000, ymx=6500,res=100,crs=mycrs) rast[]=st_intersects(st_cast(st_sfc(st_multipoint(coordinates(rast)), crs = mycrs),"POINT"),poly,sparse=FALSE) # make simple plot of raster plot(rast) # get 3D habitat mask array for 3D grid hab_mask = mask_raster(rast = rast, FUN = function(x){x==1},grid = GridX$grid, crs_ = mycrs, prev_mask = NULL) par(mfrow=c(1,2)) apply(hab_mask,3,function(x) plot(raster(apply(x,2,rev))))
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