flag_defunct_clusters: Flag Defunct Clusters

In jmsigner/amt: Animal Movement Tools

Flag Defunct Clusters

Description

Flags defunct clusters at the end of a track

Usage

flag_defunct_clusters(x, zeta, eta, theta, ...)

## S3 method for class 'track_xyt'
flag_defunct_clusters(x, zeta, eta, theta, ...)

Arguments

x	⁠[track_xyt]⁠ A track_xyt object.
zeta	⁠[numeric]⁠ See details.
eta	⁠[numeric]⁠ See details.
theta	⁠[numeric]⁠ See details.
...	Addtional arguments. None currently implemented.

Details

Locations at the end of a trajectory may represent a dropped collar or an animal mortality. In some cases, the device may be recording locations for quite some time that are not biologically meaningful. This function aims to flag those locations at the end of the trajectory that belong to a mortality (or similar) cluster. The first location at the cluster remains unflagged, but all subsequent locations are flagged.

The algorithm detects steps that represent zero movement, within a precision threshold given by zeta. That is, if zeta = 5 (units determined by CRS; typically meters), all points that differ by less than 5 will be considered zero movement. Consecutive steps of zero movement (within the tolerance) form a cluster. The parameter eta gives the cutoff for the minimum number of zero steps to be considered a cluster. Finally, the algorithm requires that clusters persist without a non-zero step for a minimum amount of time, given by theta.

Value

Returns x (a track_xyt) with a flagging column added (x$defunct_cluster_).

Author(s)

Brian J. Smith and Johannes Signer, based on code by Tal Avgar

See Also

flag_duplicates(), flag_fast_steps(), flag_roundtrips()

jmsigner/amt documentation built on April 24, 2024, 9:16 a.m.