R/calculate_course.R

In PabloMBooster/vmsR: For analysing VMS data

calculate_course <- function(lon,lat){
  output <- NULL
  for(i in 2:length(lon)){
    rad <- pi/180

    x2 <-  lon[i]*rad
    y2 <-  lat[i]*rad
    x1 <-  lon[i-1]*rad
    y1 <-  lat[i-1]*rad
    get_course <- (90 - atan2(y2-y1,x2-x1) * 180/pi ) %% 360
    output <- rbind(output,get_course)
  }
  output <- c(NA, output)

  # vectorRumbo <- NULL
  # vectorRumbo[1] <- NA
  # for(i in 2:length(lon)){
  #   x2 <-  lon[i]
  #   y2 <-  lat[i]
  #   x1 <-  lon[i-1]
  #   y1 <-  lat[i-1]
  #   y   <- sin((x2-x1)*pi/180) * cos(y2*pi/180)
  #   x   <- cos(y1*pi/180) * sin(y2*pi/180) - sin(y1*pi/180) * cos(y2*pi/180) * cos((x2-x1)*pi/180)
  #   Rumbo <- atan2(y,x)*180/pi
  #   Rumbo <- (Rumbo + 360)%%360
  #   vectorRumbo <- rbind(vectorRumbo,Rumbo)
  # }
  # vectorRumbo <- as.vector(vectorRumbo)
  # return(vectorRumbo)#, cambioRumbo = cambioRumbo))

  return(output)
}