reproducible (version 0.2.9)

fastMask: Faster operations on rasters

Description

This alternative to raster::mask is included here.

Usage

fastMask(x, y, cores = NULL,
  useGDAL = getOption("reproducible.useGDAL", TRUE))

Arguments

x

A Raster* object.

y

A SpatialPolygons object. If it is not in the same projection as x, it will be reprojected on the fly to that of x

cores

An integer* or 'AUTO'. This will be used if gdalwarp is triggered. 'AUTO'* will calculate 90 number of cores in the system, while an integer or rounded float will be passed as the exact number of cores to be used.

useGDAL

Logical, defaults to getOption("reproducible.useGDAL" = TRUE). If TRUE, then this function will use gdalwarp only when not small enough to fit in memory (i.e., if the operation fails the raster::canProcessInMemory(x, 3) test). Using gdalwarp will usually be faster than raster::projectRaster, the function used if this is FALSE. Since since the two options use different algorithms, there may be different projection results.

Value

A Raster* object, masked (i.e., smaller extent and/or several pixels converted to NA)

Examples

# NOT RUN {
library(raster)

Sr1 <- Polygon(cbind(c(2, 4, 4, 0.9, 2), c(2, 3, 5, 4, 2)))
Sr2 <- Polygon(cbind(c(5, 4, 2, 5), c(2, 3, 2, 2)))
Sr3 <- Polygon(cbind(c(4, 4, 5, 10, 4), c(5, 3, 2, 5, 5)))

Srs1 <- Polygons(list(Sr1), "s1")
Srs2 <- Polygons(list(Sr2), "s2")
Srs3 <- Polygons(list(Sr3), "s3")
shp <- SpatialPolygons(list(Srs1, Srs2, Srs3), 1:3)
d <- data.frame(vals = 1:3, other = letters[3:1], stringsAsFactors = FALSE)
row.names(d) <- names(shp)
shp <- SpatialPolygonsDataFrame(shp, data = d)
poly <- list()
poly[[1]] <- raster(raster::extent(shp), vals = 0, res = c(1, 1))
poly[[2]] <- raster(raster::extent(shp), vals = 1, res = c(1, 1))
origStack <- stack(poly)
# original mask function in raster
newStack1 <- mask(origStack, mask = shp)
newStack2 <- fastMask(x = origStack, y = shp)

# test all equal
all.equal(newStack1, newStack2)

newStack1 <- stack(newStack1)
newStack2 <- stack(newStack2)

if (interactive()) {
  plot(newStack2[[1]])
  plot(shp, add = TRUE)
}

# }