[R-sig-Geo] dynamic (interactive) representation of several GPS trajectories

[Gabriele Cozzi]

Dear list,

I have relocation data for about 20 individuals (ID) for a total of about
70K rows organised in the following data frame:
timevar <-as.numeric(Timestamp); SB is categorical with 2 levels, the other
variables are self-explanatory I think

ID       Date        Time           Timestamp              Lon       Lat
         Alti SB timevar
D 2013-01-01 18:40:00 2013-01-01 18:40:00 21.85803 -26.99953 917  0    1500
D 2013-01-01 18:55:00 2013-01-01 18:55:00 21.85877 -27.00000 921  0    2400
D 2013-01-01 19:10:00 2013-01-01 19:10:00 21.85907 -27.00015 925  0    3300
A 2013-01-01 19:27:00 2013-01-01 19:27:00 21.85875 -27.00142 922  1    4320
A 2013-01-02 06:40:00 2013-01-02 06:40:00 21.85872 -27.00142 919  1   44700
A 2013-01-02 06:55:00 2013-01-02 06:55:00 21.86060 -27.00090 916  0   45600
..    ...............     ...........           ......................
   ........      .........      ....  ..    ......

What I would like to do is to create an animated plot where I can see how
the various individuals move in relationship to each other.

The gvisMotionChart() function from the googleVis package does what I need
on a small subset of my data but it crashes if I try to do the same on the
entire data set.

A reproducible example for two individuals:
     x <- rnorm(40, 21, 0.5)
     y <- rnorm(40, -27, 0.5)
     ID <- rep(c("A","B"), each=20)
     Alt <- floor(rnorm(40, 900, 10))
     tvar <- 1:40
     tvarA <- sample(tvar,20)
     tvarB <- setdiff(tvar, tvarA)

     DF <- data.frame(ID,x,y,Alt,tvar = c(tvarA,tvarB))
     DF <- DF[order(DF$ID,DF$tvar),]

     library(googleVis)
     plot(gvisMotionChart(DF, idvar="ID", timevar= "tvar"))


An alternative along the lines of what I want would be  the
trajdyn{adehabitatLT}, even if it does not allow dynamic movements of more
than one individual at the time, which is unfortunate in my case.

Any suggestion regarding alternative packages/functions is highly
appreciated.

Thanks in advance,
Gabriele


-- 
Gabriele Cozzi
Postdoctoral Research Associate
Population Ecology Research Group
http://www.popecol.org

Zurich University
Institute of Evolutionary Biology and Environmental Studies
Winterthurerstr. 190
8057 Zurich - Switzerland
E-mail: gabriele.cozzi at uzh.ch
Office: 34-J-38
Phone: +41(0)44 635 47 56
Fax: +41(0)16355711
http://www.ieu.uzh.ch

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