detFuns {unmarked} | R Documentation |
These functions represent the currently available detection
functions used for modeling line and point transect data with
distsamp. Detection functions begin with "g", and density
functions begin with a "d".
gxhn(x, sigma) gxexp(x, rate) gxhaz(x, shape, scale) dxhn(x, sigma) dxexp(x, rate) dxhaz(x, shape, scale) drhn(r, sigma) drexp(r, rate) drhaz(r, shape, scale)
x |
Perpendicular distance |
r |
Radial distance |
sigma |
Shape parameter of half-normal detection function |
rate |
Shape parameter of negative-exponential detection function |
shape |
Shape parameter of hazard-rate detection function |
scale |
Scale parameter of hazard-rate detection function |
distsamp
for example of using these for plotting
detection function
# Detection probabilities at 25m for range of half-normal sigma values. round(gxhn(25, 10:15), 2) # Plot negative exponential distributions plot(function(x) gxexp(x, rate=10), 0, 50, xlab="distance", ylab="Detection probability") plot(function(x) gxexp(x, rate=20), 0, 50, add=TRUE, lty=2) plot(function(x) gxexp(x, rate=30), 0, 50, add=TRUE, lty=3) # Plot half-normal probability density functions for line- and point-transects par(mfrow=c(2, 1)) plot(function(x) dxhn(x, 20), 0, 50, xlab="distance", ylab="Probability density", main="Line-transect") plot(function(x) drhn(x, 20), 0, 50, xlab="distance", ylab="Probability density", main="Point-transect")