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Trajectory projection

Source: R/trajectoryProjection.R
trajectoryProjection.Rd

Performs an projection of a set of target points onto a specified trajectory and returns the distance to the trajectory (i.e. rejection) and the relative position of the projection point within the trajectory.

Usage

trajectoryProjection(
  d,
  target,
  trajectory,
  tol = 1e-06,
  add = TRUE,
  force = TRUE
)

Arguments

d

A symmetric matrix or an object of class dist containing the distance values between pairs of ecosystem states (see details).

target

An integer vector of the ecosystem states to be projected.

trajectory

An integer vector of the ecosystem states conforming the trajectory onto which target states are to be projected.

tol

Numerical tolerance value to determine that projection of a point lies within the trajectory.

add

Flag to indicate that constant values should be added (local transformation) to correct triplets of distance values that do not fulfill the triangle inequality.

force

Flag to indicate that when projection falls out of the reference trajectory for a given, the closest point in the trajectory will be used.

Value

A data frame with the following columns:

  • distanceToTrajectory: Distances to the trajectory, i.e. rejection. If there is no orthogonal projection the distance corresponds to the minimum distance to the trajectory.

  • segment: Segment that includes the projected point or the closest state.

  • relativeSegmentPosition: Relative position of the projected point within the segment, i.e. values from 0 to 1 with 0 representing the start of the segment and 1 representing its end.

  • relativeTrajectoryPosition: Relative position of the projected point within the trajectory, i.e. values from 0 to 1 with 0 representing the start of the trajectory and 1 representing its end.

Author

Miquel De Cáceres, CREAF