Frequencies of combinations of cells across two or more rasters

crossFreq() tabulates the number of cells across two or more rasters for each combination of values in the rasters. Only cells that are not NA across all rasters will be used.

Usage

# S4 method for class 'GRaster'
crossFreq(x, na.rm = TRUE, cats = TRUE, verbose = FALSE)

Arguments

x

A stack of integer/categorical GRasters.

na.rm

Logical: If TRUE (default), then only cells that are not NA across all rasters will be used. If FALSE, then for each pair of GRasters, all cells that are not NA in both rasters will be used.

cats

Logical: If TRUE (default), then replace the values of categorical rasters with their category names in the output.

verbose

Logical: If TRUE, display progress messages.

Value

A data.frame or a named list of data.frames, one per each pair of rasters in x.

See also

freq(), GRASS tool r.stats (see grassHelp("r.stats"))

Examples

if (grassStarted()) {

# Setup
library(terra)

# Example data
madElev <- fastData("madElev") # raster
madCover <- fastData("madCover") # categorical raster

# Convert to GRasters
elev <- fast(madElev) # integer raster
cover <- fast(madCover) # categorical raster

# Frequencies of integer raster values
f1 <- freq(elev)
print(f1) # have to do this sometimes if output is a data table

# Frequencies of categorical raster values
f2 <- freq(cover)
print(f2) # have to do this sometimes if output is a data table

# Frequencies of given values
f3 <- freq(elev, value = 4)
print(f3) # have to do this sometimes if output is a data table

# When a GRaster has non-integer values, they will be binned:
f4 <- freq(elev + 0.1, bins = 10)
print(f4)

# Calculate cross frequencies between rasters... both need to be integer.
elevWgs84 <- project(elev, cover)
elevClasses <- clump(elevWgs84, minDiff = 0.13) # bin elevations
names(elevClasses) <- 'elevClass'
f5 <- crossFreq(c(elevClasses, cover), na.rm = FALSE)
print(f5) # have to do this sometimes if output is a data table

}