integrateOneStepLines: Integrate Line-transect One-step function

Description

Compute exact integral of the one-step distance function for line transects.

Usage

integrateOneStepLines(object, newdata = NULL, Units = NULL)

Value

A vector of areas under distance functions. If object is a distance function and newdata is specified, the returned vector's length is nrow(newdata). If object is a distance function and newdata is NULL, returned vector's length is length(distances(object)). If object is a matrix, return's length is nrow(object).

Arguments

object: Either an Rdistance fitted distance function (an object that inherits from class "dfunc"; usually produced by a call to dfuncEstim), or a matrix of canonical distance function parameters (e.g., matrix(fit$par,1)). If a matrix, each row corresponds to a distance function and each column is a parameter. If object is a matrix, it should not have measurement units. Only quantities derived from function parameters (e.g., ESW) have units. Rdistance function parameters themselves never have units.
newdata: A data frame containing new values for the distance function covariates. If NULL and object is a fitted distance function, the observed covariates stored in object are used (behavior similar to predict.lm). Argument newdata is ignored if object is a matrix.
Units: Physical units of sighting distances if object is a matrix. Sighting distance units can differ from units of w.lo or w.hi. Ignored if object is a fitted distance function.

Details

Returned integrals are $$\int_0^{w} (\frac{p}{\theta_i}I(0\leq x \leq \theta_i) + \frac{1-p}{w - \theta_i}I(\theta_i < x \leq w)) dx = \frac{\theta_i}{p},$$ where $w = w.hi - w.lo$, $\theta_i$ is the estimated one-step distance function threshold for the i-th observed distance, and $p$ is the estimated one-step proportion.

Examples

Run this code


# A oneStep distance function on simulated data
whi <- 250
T <- 100  # true threshold
p <- 0.85 # true proportion