track_param {QuAnTeTrack}R Documentation

Print track parameters

Description

track_param() is a function to compute and print various parameters of tracks from a list of track data.

Usage

track_param(data)

Arguments

data

A track R object, which is a list consisting of two elements:

  • Trajectories: A list of interpolated trajectories, where each trajectory is a series of midpoints between consecutive footprints.

  • Footprints: A list of data frames containing footprint coordinates, metadata (e.g., image reference, ID), and a marker indicating whether the footprint is actual or inferred.

Details

This function calculates various movement parameters for each track in the provided data. It uses the following helper functions from the trajr (Animal Trajectory Analysis) package:

Value

A list of lists, where each sublist contains the computed parameters for a corresponding track. The parameters included are:

The reference direction, or 0 degrees, is considered to be along the positive x-axis. This means that angles are measured counterclockwise from the positive x-axis, with 0 degrees (or 0 degrees) pointing directly along this axis. For a detailed explanation and appropriate methods for analyzing circular data, refer to Batschelet (1981).

Sinuosity is calculated according to Benhamou (2004), as defined in equation 8. The formula used here is a refined version of the sinuosity index presented by Bovet & Benhamou (1988), which is applicable to a broader range of turning angle distributions and does not require a constant step length.

The sinuosity is computed using the formula:

S = 2 \left[ p \left( \frac{1 + c}{1 - c} + b^2 \right) \right]^{-0.5}

where:

p

is the mean step length (in meters),

c

is the mean cosine of turning angles (in radians), and

b

is the coefficient of variation of the step length (in meters).

The straightness index is defined as the ratio D/L, where:

D

is the beeline distance between the first and last points in the trajectory (in meters), and

L

is the total path length traveled (in meters).

Straightness index is based on the method described by Batschelet (1981). According to Benhamou (2004), the straightness index serves as a reliable measure of the efficiency of a directed walk. However, it is not suitable for random trajectories, as the index for a random walk tends towards zero with increasing steps. Thus, it is recommended to use this measure to compare the tortuosity of random walks only if they consist of a similar number of steps.

Logo

Logo.png

Author(s)

Humberto G. Ferrón

humberto.ferron@uv.es

Macroevolution and Functional Morphology Research Group (www.macrofun.es)

Cavanilles Institute of Biodiversity and Evolutionary Biology

Calle Catedrático José Beltrán Martínez, nº 2

46980 Paterna - Valencia - Spain

Phone: +34 (9635) 44477

References

Batschelet, E. (1981). Circular statistics in biology. Academic press, 111 Fifth Ave., New York, NY 10003, 1981, 388.

Benhamou, S. (2004). How to reliably estimate the tortuosity of an animal's path:: straightness, sinuosity, or fractal dimension?. Journal of theoretical biology, 229(2), 209-220.

Bovet, P., & Benhamou, S. (1988). Spatial analysis of animals' movements using a correlated random walk model. Journal of theoretical biology, 131(4), 419-433.

See Also

tps_to_track

Examples

# Example 1:
track_param(PaluxyRiver)

# Example 2:
track_param(MountTom)


[Package QuAnTeTrack version 0.1.0 Index]