R/shift_origin.R

In jhsiao999/peco: A Supervised Approach for Predicting Cell Cycle Progression Using Single-Cell RNA-seq Data

#' @title Shift Origin of Angles
#'
#' @description Shift the origin of the angles for visualization.
#'
#' @param phase A vector of angles (in radians).
#' 
#' @param origin the new origin of the angles.
#'
#' @return A vector of angles shifted to the new origin.
#'
#' @examples
#' # Make a vector of angles.
#' theta <- seq(0,2*pi, length.out=100)
#'
#' # Shift the origin of theta to pi.
#' theta_shifted <- shift_origin(theta, origin = pi)
#'
#' plot(x=theta, y = theta_shifted)
#'
#' @author Joyce Hsiao
#' 
#' @export
#'
shift_origin <- function(phase, origin) {
    phase2 <- phase
    if (origin > 0) {
        phase2[phase >= origin] <- phase[phase >= origin] - origin
        phase2[phase < origin]  <- (phase[phase < origin] - origin + 2*pi)
    }
    if (origin < 0) {
        a <- phase[phase >= 0 & phase< (2*pi - abs(origin))] + abs(origin)
        b <- -1*(2*pi - (phase[phase <= 2*pi &
                               phase >= (2*pi - abs(origin))])) + abs(origin)
        phase2 <- c(a,b)
    }
    return(phase2)
}