Distance-based subsampling
Draws a minimum, and optional maximum constrained, distance sub-sampling
subsample.distance( x, size, d, d.max = NULL, replacement = FALSE, latlong = FALSE, echo = FALSE )
x |
A spatial polygons or points sp object |
size |
Subsample size |
d |
Minimum sampling distance |
d.max |
Maximum sampling distance |
replacement |
(FALSE/TRUE) Subsample with replacement |
latlong |
(FALSE/TRUE) Is the data in a geographic projection |
echo |
(FALSE/TRUE) Print min and max sample distances |
A subsampled spatial polygons or points sp object
This function provides a distance constrained subsample of existing point or polygon data
Jeffrey S. Evans <jeffrey_evans@tnc.org>
library(sp)
data(meuse)
coordinates(meuse) <- ~ x+y
# Subsample with a 500m minimum sample spread
sub.meuse <- subsample.distance(meuse, size = 10, d = 500, echo = TRUE)
plot(meuse, pch=19, main="min dist = 500")
points(sub.meuse, pch=19, col="red")
# Check distances
dm <- spDists(sub.meuse)
diag(dm) <- NA
cat("\n", "Min distance for subsample", min(dm, na.rm=TRUE), "\n")
cat("Max distance for subsample", max(dm, na.rm=TRUE), "\n")
# Subsample with a 500m minimum and 3500m maximum sample spread
sub.meuse <- subsample.distance(meuse, size = 10, d = 500, d.max = 3500)
plot(meuse,pch=19, main="min dist = 500, max dist = 3500")
points(sub.meuse, pch=19, col="red")
# Check distances
dm <- spDists(sub.meuse)
diag(dm) <- NA
cat("Min distance for subsample", min(dm, na.rm=TRUE), "\n")
cat("Max distance for subsample", max(dm, na.rm=TRUE), "\n")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.