mkde (version 0.4)

computeContourValues: Find thresholds for contour intervals

Description

Find the cell or voxel probabilities that correspond to user-specified probability contours

Usage

computeContourValues(mkde.obj, prob)

Value

A data frame with the probabilities given in the prob argument and corresponding thresholds in the MKDE

Arguments

mkde.obj

An MKDE object with density initialized

prob

Probabilities (i.e. proportions) for desired contours of the MKDE

Author

Jeff A. Tracey, PhD
USGS Western Ecological Research Center, San Diego Field Station

James Sheppard, PhD
San Diego Zoo Institute for Conservation Research

Details

This function computes threshold cell or voxel probability values corresponding to contours for specified proportions of the utilization distribution. Note that the arugment prob specifies the cumulative probability of the cells or voxels within the contour corresponding to the cell or voxel threshold probability. The cell or voxel threshold probabilities may be orders of magnitude smaller than the cumulative probabilities provided in the prob argument.

Examples

data(condor)

# Find min/max coordinates and add buffer
xmax = max(condor$x) + 1000
xmin = min(condor$x) - 1000
ymax = max(condor$y) + 1000
ymin = min(condor$y) - 1000

# Calculate grid dimensions
xrange <- xmax - xmin
yrange <- ymax - ymin
cell.sz = 150
nx <- as.integer(xrange/cell.sz)
ny <- as.integer(yrange/cell.sz)

mv.dat <- initializeMovementData(condor$t, condor$x, condor$y, sig2obs=25.0, t.max=185.0)
mkde.obj <- initializeMKDE2D(xmin, cell.sz, nx, ymin, cell.sz, ny)
dens.res <- initializeDensity(mkde.obj, mv.dat)

mkde.obj <- dens.res$mkde.obj
mv.dat <- dens.res$move.dat
my.quantiles <- c(0.95, 0.75, 0.50)
res <- computeContourValues(mkde.obj, my.quantiles)
print(res)