centroid_group: Group centroid

In ropensci/spatsoc: Group Animal Relocation Data by Spatial and Temporal Relationship

Group centroid

Description

centroid_group calculates the centroid (mean location) of all individuals in each spatiotemporal group identified by group_pts. The function accepts a data.table with relocation data appended with a group column from group_pts. Relocation data should be in two columns representing the X and Y coordinates.

Usage

centroid_group(DT = NULL, coords = NULL, group = "group", na.rm = FALSE)

Arguments

DT	input data.table with group column generated with group_pts
coords	character vector of X coordinate and Y coordinate column names. Note: the order is assumed X followed by Y column names.
group	Character string of group column
na.rm	if NAs should be removed in calculating mean location, see mean

Details

The DT must be a data.table. If your data is a data.frame, you can convert it by reference using data.table::setDT or by reassigning using data.table::data.table.

The coords and group arguments expect the names of a column in DT which correspond to the X and Y coordinates and group columns. The na.rm argument is passed to the mean function to control if NA values are removed before calculation.

Value

centroid_group returns the input DT appended with centroid columns for the X and Y coordinate columns.

These columns represents the centroid coordinate columns. The naming of these columns will correspond to the provided coordinate column names prefixed with "centroid_".

A message is returned when centroid columns are already exists in the input DT, because they will be overwritten.

See Also

group_pts

Other Centroid functions: centroid_dyad(), centroid_fusion()

Examples

# Load data.table
library(data.table)


# Read example data
DT <- fread(system.file("extdata", "DT.csv", package = "spatsoc"))

# Cast the character column to POSIXct
DT[, datetime := as.POSIXct(datetime, tz = 'UTC')]

# Temporal grouping
group_times(DT, datetime = 'datetime', threshold = '20 minutes')

# Spatial grouping with timegroup
group_pts(DT, threshold = 5, id = 'ID',
          coords = c('X', 'Y'), timegroup = 'timegroup')

# Calculate group centroid
centroid_group(DT, coords = c('X', 'Y'), group = 'group', na.rm = TRUE)

ropensci/spatsoc documentation built on Feb. 12, 2025, 7:16 a.m.