mosaic: Merge Raster* objects, using a function to compute cell value for overlapping areas. See `merge` for a simpler apporach.

Description

Mosaic Raster* objects to form a new object with a larger spatial extent. A functions is used to compute cell values in areas where layers overlap (in contrast to the merge function which uses the values of the 'upper' layer). All objects must have the same origin, resolution, and coordinate reference system.

Usage

## S3 method for class 'Raster,Raster':
mosaic(x, y, ..., fun, tolerance=0.05, filename="")

Arguments

Raster* object

...

Additional Raster or Extent objects (and/or arguments for writing files as in writeRaster)

fun

Function. E.g. mean, min, or max. Must be a function that accepts a 'na.rm' argument

tolerance

Numeric. Permissable difference in origin (relative to the cell resolution). See all.equal

filename

Character. Output filename (optional)

Value

RasterLayer or RasterBrick object.

Details

The Raster objects must have the same origin and resolution.

Examples

Run this code

r <- raster(ncol=100, nrow=100)
r1 <- crop(r, extent(-10, 11, -10, 11))
r2 <- crop(r, extent(0, 20, 0, 20))
r3 <- crop(r, extent(9, 30, 9, 30))

r1[] <- 1:ncell(r1)
r2[] <- 1:ncell(r2)
r3[] <- 1:ncell(r3)

m1 <- mosaic(r1, r2, r3, fun=mean)

s1 <- stack(r1, r1*2)
s2 <- stack(r2, r2/2)
s3 <- stack(r3, r3*4)
m2 <- mosaic(s1, s2, s3, fun=min)