Compute nearest neighbour distances for a single time point

Low-level function that computes distances to the nth nearest individual. For each focal point, finds the closest point belonging to the nth nearest individual (ranked by minimum distance). Called by calculate_nnd() for each time point.

Usage

compute_nnd(
  x,
  y,
  z = NULL,
  individual,
  keypoint = NULL,
  n = 1L,
  keypoint_neighbour = NULL
)

Arguments

x

Numeric vector of x coordinates.

y

Numeric vector of y coordinates.

z

Numeric vector of z coordinates, or NULL for 2D data.

individual

Factor or vector identifying which individual each point belongs to.

keypoint

Factor or vector identifying keypoint labels, or NULL if no keypoints.

n

Which individual to find (1 = nearest, 2 = second nearest, etc.).

keypoint_neighbour

Character vector of keypoint(s) to consider as valid neighbours, or NULL to consider all.

Value

A tibble with columns:

• nnd_individual: individual ID of the n-th nearest individual

• nnd_keypoint: keypoint of the closest point on that individual (only if keypoint is not NULL)

• nnd_distance: distance to the closest point on the n-th nearest individual

See also

calculate_nnd() for the user-facing aniframe function