thin: Spatial thinning of occurrence records.

In red: IUCN Redlisting Tools

Spatial thinning of occurrence records.

Description

Thinning of records with minimum distances either absolute or relative to the species range.

Usage

thin(longlat, distance = 0.01, relative = TRUE, runs = 100)

Arguments

longlat	Matrix of longitude and latitude or eastness and northness (two columns in this order) of species occurrence records.
distance	Distance either in relative terms (proportion of maximum distance between any two records) or in raster units.
relative	If TRUE, represents the proportion of maximum distance between any two records. If FALSE, is in raster units.
runs	Number of runs

Details

Clumped distribution records due to ease of accessibility of sites, emphasis of sampling on certain areas in the past, etc. may bias species distribution models. The algorithm used here eliminates records closer than a given distance to any other record. The choice of records to eliminate is random, so a number of runs are made and the one keeping more of the original records is chosen.

Value

A matrix of species occurrence records separated by at least the given distance.

Examples

records <- matrix(sample(100), ncol = 2)
par(mfrow=c(1,2))
graphics::plot(records)
records <- thin(records, 0.1)
graphics::plot(records)

red documentation built on Sept. 9, 2023, 1:07 a.m.