utilizationDistribution: Compute utilization distribution for a trajectory
In moveBB: Analysis of Trajectory Data using Linear or Brownian Motion Model

Description Usage Arguments Details Value Examples

This function computes the utilization distribution (UD) for each of the IDs present in the trajectory. The user may specify the grid on which the UD is evaluated and may also specify the size of the time step in the numerical integration.

utilizationDistribution(tr, grid=NULL, timestepSize = 60,
    xc=NULL, yc=NULL, grid.dim = 100, grid.pad = 0.2,
    byburst = FALSE, cutoff.level = 1)
utilizationDistribution.byID(ud)

`tr`	The trajectory for which to compute the UD
`grid`	a grid of class `asc`
`timestepSize`	The difference between consecutive time steps, in seconds
`xc`	The x coordinates of the vertical grid lines
`yc`	The y coordinates of the horizontal grid lines
`grid.dim`	If all of `grid`, `xc` and `yc` are omitted, this specifies the dimension of the shortest axis of the grid used.
`grid.pad`	If the grid is automatically generated, its range is the range of the relocations extended `grid.pad` times the length of the range on each side.
`byburst`	Whether the result should be a UD for each burst.
`cutoff.level`	What fraction of the UD volume must be actually stored.
`ud`	The result of `utilizationDistribution` with `byburst=TRUE`

One can specify the grid in three ways:

If grid is set, the coordinates of the grid lines are derived from there.
These coordinates can also be specified in the parameters xc and yc.
Otherwise, the grid is determined automatically. The grid then ranges over a bounding box of all measurements, extended on each side by a specified fraction of the range. The number of grid cells can be controlled via grid.dim. The amount by which the grid is extended is controlled via grid.pad, which may be a vector specifying the extension on top,right,bottom,left respectively. It is recycled as usual.

If cutoff.level is set to a value less than 1, the result will not store a utilization distribuiton for the full grid, but instead an axis-aligned box that contains the full contour at the requested level.

When a UD is extracted from a list containing such partial UDs, the cells that were left out are restored and filled with zeros.

utilizationDistribution.byID can be used to convert the result of utilizationDistribution with byburst=TRUE to a result that is aggregated by ID.

Returns a list, indexed by the IDs in tr. If grid is given, each element of the result list is an object of class asc, representing the same grid. Otherwise, each element of the list is a matrix, indexed by the coordinates specified in xc and yc.

data("vervet_monkeys", package="moveBB")

# Compute the UD and plot the result
#ud <- utilizationDistribution(monkey.tr, byburst=TRUE)
#plot(ud)

# Convert to one UD for each group
#ud <- utilizationDistribution.byID(ud)
#plot(ud)