Change options() to keep millisecond information. Copy raw data and c…

…hange by reference.

R/prepFiles.R

@@ -7,16 +7,49 @@
 #' prepped_detections <- prepDetections("path-to-raw-data-file", type="vemco_vue")
 #' }
 prepDetections <- function(raw_dat, type){
-	detections <- data.table::data.table()
+
+  # gsub (and the previous version using strsplit) convert to character before
+  #   doing their thing. The default number of millisecond digits for R to
+  #   display is 0, so millisecond information is dropped when converted to
+  #   character. Temporarily change this to keep milliseconds, then used on.exit
+  #   to change the option back to what it was before when the function finishes
+  op <- options(digits.secs = 3)
+  on.exit(options(op), add = T)
+
+	detections <- data.table::copy(raw_dat)
+
 	if (type == "vemco_vue"){
-	  detections[, ts := as.POSIXct(raw_dat$'Date and Time (UTC)', tz = "UTC")]
-	  detections[, tag := as.numeric(gsub('.*-', '', raw_dat$Transmitter))]
-	  detections[, epo := as.numeric(ts)]
-	  detections[, frac := as.numeric(gsub('.*\\.', '',
-	                                       raw_dat$"Date and Time (UTC)")) / 1000]
-	  detections[, serial := as.numeric(gsub('.*-', '', raw_dat$Receiver))]
+
+	  # Only parse datetime if needed
+	  ##  trunc drops milliseconds but converts to POSIXlt in the process, so it needs
+	  ##  to be converted back to POSIXct for use elsewhere.
+
+	  if(!inherits(detections$`Date and Time (UTC)`, 'POSIXt')){
+
+	    detections[, ts :=
+	                 as.POSIXct(
+	                   trunc(
+	                     as.POSIXct(`Date and Time (UTC)`, tz = "UTC")
+	                   )
+	                 )]
+
+	  } else{
+
+	    detections[, ts :=
+	                 as.POSIXct(
+	                   trunc(`Date and Time (UTC)`)
+	                 )]
+
+	  }
+
+	  detections[, ':='(tag = as.numeric(gsub('.*-', '', Transmitter)),
+	                    epo = as.numeric(ts),
+	                    frac = as.numeric(gsub('.*\\.', '',
+	                                            `Date and Time (UTC)`)) / 1000,
+	                    serial = as.numeric(gsub('.*-', '', Receiver)))]
 	}
-	detections[]
-	return(detections)
+
+	detections[, .(ts, tag, epo, frac, serial)]
+
 }