calcAreas {unmarked} | R Documentation |
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.
calcAreas(dist.breaks, tlength, survey, output, M, J, unitsIn, unitsOut)
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" |
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.
This function might be useful if some distance classes for some
transects were not surveyed. In such a case, missing values could be added
to the output of calcAreas and the modified matrix could be supplied
to the plotArea argument of unmarkedFrameDS
.
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")