R/utility_functions.R

In Middleton-Lab/KinematicAnalysis: 3D kinematic data analysis

#' Dot product
#'
#' @param u Numeric vector
#' @param v Numeric vector
#'
#' @return Numeric dot product of `u` and `v`.
#'
dot <- function(u, v) {
  return(sum(u * v))
}


#' Radians to degrees
#'
#' @param r Numeric vector of radians
#'
#' @return Vector with r converted to degrees
#'
rad2deg <- function(r) {
  return(r * 180 / pi)
}


#' Convert wide data to (x, y, z) rows
#'
#' @param d Data.frame with points in wide format
#'
#' @return Data.frame with (x, y, z) points as rows 1, 2, and 3
#'
make_xyz_matrix <- function(d) {
  n_rows <- 3
  n_col <- ncol(d) / 3
  return(matrix(as.numeric(d), nrow = n_rows, ncol = n_col, byrow = FALSE))
}


#' 3d distance
#'
#' @param p1 numeric vector: length of 3
#' @param p2 numeric vector: length of 3
#'
#' @return numeric: 3d distance between p1 and p2
#'
dist_3d <- function(p1, p2) {
  d <- sqrt((p1[1] - p2[1]) ^ 2 + (p1[2] - p2[2]) ^ 2 + (p1[3] - p2[3]) ^ 2)
  return(as.numeric(d))
}