gridDistance {terra}

R Documentation

Distance on a grid

Description

The function calculates the distance to cells of a SpatRaster when the path has to go through the centers of the eight neighboring raster cells.

The distance is in meters if the coordinate reference system (CRS) of the SpatRaster is longitude/latitude (+proj=longlat) and in the units of the CRS (typically meters) in other cases.

Distances are computed by summing local distances between cells, which are connected with their neighbors in 8 directions.

Usage

## S4 method for signature 'SpatRaster'
gridDistance(x, target=0, scale=1000, maxiter=50, filename="", ...) 

Arguments

x	SpatRaster
target	numeric. value of the target cells (where to compute distance to)
scale	numeric. Scale factor for longitude/latitude data (1 = m, 1000 = km)
maxiter	numeric. The maximum number of iterations. Increase this number if you get the warning that costDistance did not converge
filename	character. output filename (optional)
...	additional arguments as for writeRaster

Value

SpatRaster

Note

see terra:::.oldGridDistance for the previous version of this method (will be removed in a future version)

See Also

See distance for "as the crow flies" distance

Examples

Run examples

# global lon/lat raster
r <- rast(ncol=10,nrow=10, vals=1)
r[48] <- 0
r[66:68] <- NA
d <- gridDistance(r) 
plot(d)


# planar
crs(r) <- "+proj=utm +zone=15 +ellps=GRS80 +datum=NAD83 +units=m +no_defs"
d <- gridDistance(r) 
plot(d)

# distance to cells that are not NA 
rr <- classify(r, cbind(1, NA))
dd <- gridDistance(rr, NA) 

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