unmarked (version 0.8-5)

calcAreas: Prepare area argument for distsamp.

Description

Prepare area argument for distsamp. This is primarily for internal use but see details. Caution should be used because the returned matrix has different interpretations for different survey and output types.

Usage

calcAreas(dist.breaks, tlength, survey, output, M, J,
    unitsIn, unitsOut)

Arguments

dist.breaks

numeric vector of distance class break poings

tlength

numeric vector of transect lengths for line transects

M

number of transects

J

number of distance classes

survey

either "line" or "point"

output

either "abund" or "density"

unitsIn

either "m" or "km" for units of both dist.breaks and tlength.

unitsOut

either "ha" or "kmsq"

Value

• An M x J numeric matrix.

  If output == "density" and survey == "line" then the values are the areas of each distance class for each transect. If output == "density" and survey == "point" then the values are the the radii of each point transect. Currently, radii cannot vary.

  If survey == "point" and output == "abund" a matrix of 1s is returned. If survey == "line" and output == "abund" a matrix of transect lengths is returned because transect lengths must be taken into account even if density is not of interest.

See Also

distsamp, unmarkedFrame

Examples

data(linetran)
(dbreaksLine <- c(0, 5, 10, 15, 20)) 
lengths <- linetran$Length * 1000

calcAreas(dbreaksLine, lengths, "line", "density", M=nrow(linetran), 
	J = length(dbreaksLine) - 1, "m", "ha")

data(pointtran)
(dbreaksPt <- seq(0, 25, by=5))

calcAreas(dbreaksPt, survey="point", output="density", M=nrow(pointtran),
	J = length(dbreaksPt) - 1, unitsIn = "m", unitsOut = "ha")