Get spatially discretized heading and speed over time

Gets spatially discretized heading for a given individual trajectory This is defined as the unit vector pointing from the individual's current location at time t to its location after it mas moved a distance of at least R.

Usage

get_heading_and_speed_spatial(
  x_i,
  y_i,
  R,
  t_idxs = 1:length(x_i),
  forward = T,
  seconds_per_time_step = 1
)

Arguments

x_i

vector of x coordinates for the trajectory

y_i

vector of y coordinates for the trajectory

R

radius used to compute the headings

t_idxs

time indexes at which to compute the headings, speed, dts (defaults to entire trajectory)

forward

whether to go forward in time from current position (if T), or backward (if F) when computing headings

seconds_per_time_step

number of seconds corresponding to each time step

Value

Returns a list containing

• $heads: a time series of the heading of the individual (a vector of the same length as x_i and y_i), in radians, computed based on spatial discretization around the time point

• $speeds: a time series of the average speed of the individual from the first point outside radius R to the current point

• $dts: time differences between the current point and the first point outside of the radius R (either forward or backward in time)

vector of spatially discretized headings, computed at all times or at times t_idxs if specified (other times are then filled in with NAs)

Author

Ariana Strandburg-Peshkin (primary author)

Reviewed by Brock