detFuns: Distance-sampling detection functions and associated density... In unmarked: Models for Data from Unmarked Animals

Description

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".```

Usage

 ``` 1 2 3 4 5 6 7 8 9 10``` ```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) ```

Arguments

 `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

Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```# 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") ```

Example output

```Loading required package: lattice
[1] 0.04 0.08 0.11 0.16 0.20 0.25
```

unmarked documentation built on May 27, 2021, 5:07 p.m.