R/CTDtimeandpos.R

In arnejohannesholmin/sonR: Library for reading, processing and converting sonar data to the TSD format

#*********************************************
#*********************************************
#' Reads the time and position of a CTD file in the cnv format.
#'
#' @param x  is a CTD file in the cnv format.
#'
#' @return
#'
#' @examples
#' \dontrun{}
#'
#' @export
#' @rdname CTDtimeandpos
#'
CTDtimeandpos<-function(x){
	
	if(isTRUE(file.exists(x))){
		x=readLines(x)
	}
	start = substr(x,1,18)
	atlat = tolower(start) == "* nmea latitude = "
	atlon  = tolower(start) == "* nmea longitude ="
	attime  = tolower(start) == "* system upload ti"
	utim = unclass(as.POSIXct(strptime(substring(x[attime],24),"%b %d %Y %H:%M:%S")))
	lat = strsplit(substr(x[atlat],19,nchar(x[atlat])-1)," ",fixed=TRUE)[[1]]
	lat = as.numeric(lat[nchar(lat)>0])
	lon = strsplit(substr(x[atlon],19,nchar(x[atlon])-1)," ",fixed=TRUE)[[1]]
	lon = as.numeric(lon[nchar(lon)>0])
	lat = lat[1] + lat[2]/60
	lon = lon[1] + lon[2]/60
	North = substring(x[atlat],nchar(x[atlat])) == "N"
	East = substring(x[atlon],nchar(x[atlon])) == "E"
	if(!North){
		lat = -lat
	}
	if(!East){
		lon = -lon
	}
	
	
	c(utim=utim, lat=lat, lon=lon)
}