recstrat_prop: Random Ecologically Stratified Sampling of propotional...

In filBe87/PKUss: Helper functions for species distribution modelling practicals of the Peking Unversity summer school 2019

Description

This function randomly collects a user-defined total number of samples from the stratification layer.

Usage

recstrat_prop(in_grid, sample_no)

Arguments

in_grid	The stratification grid to be sampled.
sample_no	The total number of pixels to be sampled.

Details

The number of samples per class are determined proportional to the abundance of each class. The number of classes in the stratification layer are determined automatically from the integer input map. If the proportion of samples for a certain class is below one then no samples are collected for this class.

Value

Returns a dataframe with the selected sampling locations their coordinates and the strata they belong in.

Author(s)

Achilleas Psomas, Niklaus Zimmermann

Examples

bio3<- raster(system.file("external/bioclim/current/bio3.grd",package="biomod2"))
bio12<- raster(system.file("external/bioclim/current/bio12.grd",package="biomod2"))
B3.rcl<-rcls.grd(bio3,9)
B12.rcl<-rcls.grd(bio12,9)
B3B12.comb <- B12.rcl+B3.rcl*10
B3B12.prop_samples <- recstrat_prop(B3B12.comb,100)
plot(B3B12.comb)
points(B3B12.prop_samples$x,B3B12.prop_samples$y,pch=16,cex=0.6,col=B3B12.prop_samples$class)

filBe87/PKUss documentation built on June 29, 2019, 12:12 a.m.