Hello everyone,

I'm trying to create a ltraj-class.
I start with importing an excel file containing all the relocations (in this case for the month March) into ArcMap and create a shapefile. Next I load the shapefile into R and transform the coordinates to UTM37S.

My dataset looks as follows:

head(march2012)
 coordinates                           ID                                       Date_old        Longitude   Latitude           Date
0 (496297, 9688770)  Emusaya_Male  2012-03-20   38.96668   -2.815783  2012-03-20 00:04
1 (496670, 9686680)  Emusaya_Male  2012-03-20   38.97003   -2.834650  2012-03-20 01:04
2 (497136, 9685230)  Emusaya_Male  2012-03-20   38.97423   -2.847833  2012-03-20 02:04
3 (497233, 9684700)  Emusaya_Male  2012-03-20   38.97510   -2.852633  2012-03-20 03:05
4 (497105, 9684290)  Emusaya_Male  2012-03-20   38.97395   -2.856317  2012-03-20 04:04
5 (497281, 9683830)  Emusaya_Male  2012-03-20   38.97553   -2.860467  2012-03-20 05:04

I used the following script:
da <- as.character(march2012$Date)
da <- as.POSIXct(strptime(as.character(march2012$Date),"%y-%m-%d  %H:%M"))
march2012df <- as.data.frame(march2012)
xymarch2012 <- coordinates(march2012)
elemarch2012 <- as.ltraj(xy =xymarch2012, date = da, id = march2012df$ID)

There error message I got was: "Error in as.ltraj(xy = xymarch2012, date = da, id = march2012df$ID) : 
  non unique dates for a given burst".

Before posting this message, I read about duplicates. My dataset includes 10 different elephants, so it could be that some dates are the same. However, I would like to keep these locations because they are different individuals.

I hope I made my problem clear. If you need any more information, please let me know what kind of information and how to send it.

Kind regards,

Nick van Doormaal
MSc student Forest and Nature Conservation
Wageningen University, The Netherlands 		 	   		  
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