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