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
|
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:
-
TrajAngles()
: Calculates the turning angles of the track. -
TrajDistance()
: Calculates the total distance covered by the track. -
TrajLength()
: Calculates the length of the track. -
TrajStepLengths()
: Calculates the step lengths of the track. -
TrajSinuosity2()
: Calculates the sinuosity of the track. -
TrajStraightness()
: Calculates the straightness of the track.
Value
A list of lists, where each sublist contains the computed parameters for a corresponding track. The parameters included are:
-
Turning_angles
: A vector of turning angles for the track (in degrees). -
Mean_turning_angle
: The mean of the turning angles (in degrees). -
Standard_deviation_turning_angle
: The standard deviation of the turning angles (in degrees). -
Distance
: The total distance covered by the track (in meters). -
Length
: The length of the track (in meters). -
Step_lengths
: A vector of step lengths for the track (in meters). -
Mean_step_length
: The mean of the step lengths (in meters). -
Standard_deviation_step_length
: The standard deviation of the step lengths (in meters). -
Sinuosity
: The sinuosity of the track (dimensionless). -
Straightness
: The straightness of the track (dimensionless).
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
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
Examples
# Example 1:
track_param(PaluxyRiver)
# Example 2:
track_param(MountTom)