crosstabm: create a contingency table between a comparison raster map (rows) and a reference raster map (columns)

Description

create a contingency table, also called cross-tabulated matrix, between a comparison raster map (rows), or map at time t, and a reference raster map (columns), or map at time t+1

Usage

crosstabm(comp, ref, percent = FALSE, population = NULL)

Value

a matrix showing the cross-tabulation between the comparison map (or map at time t) and the reference map (or map at time t+1)

Arguments

comp: object of class SpatRaster corresponding to the comparison map, or map at time t
ref: object of class SpatRaster corresponding to the reference map, or map at time t+1
percent: logical. If TRUE, output values are given as percentage. If FALSE, output values are given in pixel counts
population: an n x 2 matrix provided to correct the sample count to population count in the square contingency table. See Details below

Details

For correcting the sample count to population count in the square contingency table, assuming a stratified random sampling, an n (number of categories) by 2 matrix can be provided in the population argument. The first column of population must contains integer identifiers of each category, corresponding to the categories in the comparison map (or map at time t) and reference map (or map at time t+1). The second column corresponds to the population totals for each map category

Examples

Run this code

comp <- rast(system.file("external/comparison.rst", package = "diffeR"))
ref <- rast(system.file("external/reference.rst", package = "diffeR"))
crosstabm(comp, ref)

# Population-adjusted square contingency table
(population <- matrix(c(1, 2, 3, 2000, 4000, 6000), ncol = 2))
crosstabm(comp, ref, population = population)

# Population-adjusted square contingency table, output as percentage
crosstabm(comp, ref, percent = TRUE, population = population)