Hi

I am using adehabitat to calculate first passage time (fpt) for a series of GPS locations at a specific date and time.

When I use as.ltraj to workout trajectories the output I get for each data point looks like this:

x                     y                 date                                     dx   dy   dist  dt    R2n    abs.angle    rel.angle
-6.070993  51.59435  2006-06-17 15:03:04     NA  NA  NA   NA   0        NA      102        NA

When I use fpt I get a series of NA for all points and I'm guessing this is to do with the NAs for dx/dy/dt from ltraj.  Does anyone know what may be causing this error?

The full code is below

Thanks!

Sam

FOR LTRAJ
str(dddate)
dddate<-as.character(dddate)
str(dddate)
tttime<-as.character(tttime)
datetime<-paste(dddate, tttime)
ddate <- as.POSIXct(datetime)
xy<-data.frame (x, y)
id<-data.frame (FPT[,5])
xy<-data.frame (FPT[,4], FPT[,3])
yaya<-as.ltraj(xy,ddate,id, burst, typeII = TRUE, slsp = c("remove", "missing"))

FOR FPT
fptyaya=fpt(yaya, seq(300,1000,length=30))



Dr Samantha Patrick
EU INTERREG Post Doc
Marine Biology & Ecology Research Centre
University of Plymouth
Plymouth
PL4 8AA

T: 01752 584699
M: 07740472719


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