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Mask all non-NA cells or all NA cells

Source: R/maskNA.r
maskNA.Rd

This function work in two ways:

  • If byLayer = TRUE (default), it will convert all non-NA cells in a GRaster to a single user-defined value, leaving NA cells as NA. Alternatively, it can convert NA cells to a user-defined value, and all non-NA cells to NA. Regardless, if the input is a "stack" of GRasters, it will return a stack with the same number of raster layers.

  • If byLayer = FALSE and x is a "stack" of GRasters,, it will return a single GRaster layer. This layer will have a user-defined value in all cells that had no NAs across all rasters, and NAs in cells where at least one raster had an NA. This is useful for masking out areas where data are missing in any of the rasters. If invert = TRUE, it will return a single GRaster layer with a user-defined value in all cells that had at least one NA across all rasters, and NAs in cells where all rasters had non-NA values.

Usage

# S4 method for class 'GRaster'
maskNA(x, value = 1, invert = FALSE, retain = FALSE, byLayer = TRUE)

Arguments

x

A GRaster.

value

Numeric: Value to which to assign to masked cells. The default is 1.

invert

Logical: If FALSE (default), convert non-NA cells to value, and leave NA cells as-is. If TRUE, convert all NA cells to value, and non-NA cells to NA.

retain

Logical: If invert is TRUE and retain is FALSE (default), non-NA cells will retain their value. This argument is ignored if invert is FALSE. Ignored if byLayer = FALSE.

byLayer

Logical: If TRUE (default), implement the masking layer-by-layer. If x is a stack of raster, it will return a stack with the same number of layers. If FALSE, return a single raster layer with NA in all cells that had at least one NA across all layers, and value in all cells that had no NAs across all layers. If invert = TRUE, it will return a single raster layer with value in all cells that had at least one NA across all layers, and NA in all cells that had no NAs across all layers.

Value

A GRaster.

See also

not.na(), app(), mask()

Examples

if (grassStarted()) {

# Setup
library(terra)

### Mask layer-by-layer

# Elevation raster
madElev <- fastData("madElev")

# Convert a SpatRaster to a GRaster:
elev <- fast(madElev)

# Convert non-NA to 1, NA cells remain NA
elevMask <- maskNA(elev)
elevMask
plot(c(elev, elevMask))

# Convert NA to 1, non-NA cells become NA
elevInvertMask <- maskNA(elev, invert = TRUE)
elevInvertMask
plot(c(elev, elevInvertMask))

# Convert NA to 200, non-NA cells keep their values
elevInvertRetain <- maskNA(elev, value = 200, invert = TRUE, retain = TRUE)
elevInvertRetain
plot(c(elev, elevInvertRetain))

### Mask *across* layers

# Load forest raster, which has many NAs
madForest2000 <- fastData("madForest2000")
forest2000 <- fast(madForest2000)

x <- c(elev, forest2000)

maskByLayer <- maskNA(x)
maskAcrossLayers <- maskNA(x, byLayer = FALSE)

maskByLayer
maskAcrossLayers

}