estSpaceUse {track2KBA} | R Documentation |
Estimate the space use of tracked animals using kernel utilization distribution
Description
estSpaceUse
is a wrapper for kernelUD
which estimates the utilization distribution (UD) of multiple individuals or
tracks in a tracking dataset.
Usage
estSpaceUse(tracks, scale, levelUD, res = NULL, polyOut = FALSE)
Arguments
tracks |
SpatialPointsDataFrame. Must be projected into an equal-area
coordinate system. If not, first run |
scale |
numeric (in kilometers). The smoothing parameter ('H') used in
the kernel density estimation, which defines the width of the normal
distribution around each location. The |
levelUD |
numeric (percent). Specify which utilization distribution
contour at which to subset the polygon output. NOTE: This will only affect
the output if |
res |
numeric (in square kilometers). Grid cell resolution for kernel density estimation. Default is a grid of 500 cells, with spatial extent determined by the latitudinal and longitudinal extent of the data. |
polyOut |
logical scalar (TRUE/FALSE). If TRUE then output will include
a plot of individual UD polygons and a simple feature with kernel UD polygons
for the level of |
Details
A utilization distribution will be calculated for each unique 'ID'. The data should be regularly sampled or interpolated (see adehabitatLT package for functions to this end).
If desired res
results in memory-heavy grid (e.g. >10,000 cells)
use polyOut = FALSE
to speed things up.
Value
Returns an object of class estUDm
which is essentially a list,
with each item representing the utilization distribution of a level of 'ID'.
Values in the output signify the usage probability per unit area for that
individual in each grid cell. This can be converted into a
SpatialPixelsDataFrame via the adehabitatHR::estUDm2spixdf
function.
If polyOut=TRUE
the output will be a list with two components:
'KDE.Surface' is the estUDm
object and UDPolygons
is
polygon object of class sf
(Simple Features) with the UD contour for
each individual at the specified levelUD
.
If polyOut=TRUE
but the polygon delineation in
adehabitatHR::getverticeshr
fails, output is an object of class
estUDm
and a warning will be issued.
See Also
formatFields
, tripSplit
,
findScale
Examples
library(sf)
library(sp)
library(magrittr)
## make some play data
dataGroup <- data.frame(
Longitude = c(1, 1.01, 1.02, 1.04, 1.05, 1.03, 1),
Latitude = c(1, 1.01, 1.02, 1.03, 1.021, 1.01, 1),
ID = rep("A", 7),
DateTime = format(
lubridate::ymd_hms("2021-01-01 00:00:00") +
lubridate::hours(0:6)
)
)
tracks <- sf::st_as_sf(
dataGroup, coords = c("Longitude", "Latitude"),
crs = 4326, agr = "constant") %>%
sf::st_transform(crs = 32631) %>%
sf::as_Spatial()
## estimate utilization distributions for each track
KDE <- estSpaceUse(tracks, scale=10, levelUD = 50)