R/ConvertPointsToCircuitousDistance.R

In RossDwyer/VTrack: A Collection of Tools for the Analysis of Passive Acoustic Telemetry Data

ConvertPointsToCircuitousDistance <- 
function(sInputFile)
{
  iCount <- 0
  iLog <- 0
  rDistance <- 0
  rPreviousLat <- 0
  rPreviousLon <- 0
  sPreviousRECEIVERID <- ""
  
  # create output files 
  outfile <- data.frame(RECEIVERID1=sInputFile[1,1],RECEIVERID2=sInputFile[1,1],DISTANCE=0,stringsAsFactors=FALSE)[NULL,]
  
  while (iCount < nrow(sInputFile))
  {
    iCount <- iCount + 1
    sRECEIVERID <- sInputFile[iCount,1]
    rLat <- sInputFile[iCount,2]
    rLon <- sInputFile[iCount,3]
    
    if(class(sRECEIVERID)=="integer"){
      if (iCount > 1)
      {
        # compute distance from previous point
        rSegmentDistance <- ComputeDistance(rLat,rPreviousLat,rLon,rPreviousLon)
        rDistance <- rDistance + rSegmentDistance
        if (sRECEIVERID != 0)
        {
          iLog <- iLog + 1 
          # write record to outfile
          outfile[iLog,] <- c(sPreviousRECEIVERID,sRECEIVERID,rDistance)
          rDistance <- 0
        }
      }
      rPreviousLat <- rLat
      rPreviousLon <- rLon
      if (sRECEIVERID != 0 | sRECEIVERID != "0")
      {
        sPreviousRECEIVERID <- sRECEIVERID
      }
    }
    
    if(class(sRECEIVERID)=="character"){
      if (iCount > 1)
      {
        # compute distance from previous point
        rSegmentDistance <- ComputeDistance(rLat,rPreviousLat,rLon,rPreviousLon)
        rDistance <- rDistance + rSegmentDistance
        if (sRECEIVERID != "0")
        {
          iLog <- iLog + 1 
          # write record to outfile
          outfile[iLog,] <- c(as.character(sPreviousRECEIVERID),as.character(sRECEIVERID),rDistance)
          rDistance <- 0
        }
      }
      rPreviousLat <- rLat
      rPreviousLon <- rLon
      if (sRECEIVERID != "0")
      {
        sPreviousRECEIVERID <- as.character(sRECEIVERID)
      }
    }
    
  }
  return(outfile)
}