Ahoi again!
I am not sure, if this works exactly as you wish, but maybe it helps:
#this function gives TRUE for the first observation on each day when a new 10
days sequence starts
foo3 <- function(date) {
tmp <- as.Date(date) #in this format i can add 10 days without
problems
tmp1 <- date #to develop the function
days <- levels(as.factor(tmp)) #what days do we have?
sel_int <- rep(F,length(days)) #vector creation to mark the time steps
(in the days)
mark <- seq(1,length(sel),10) #10 days sequece
sel_int[mark] <- T #all 10 days we have a TRUE
sel_ext <- rep(F,length(date)) #the marked vektor to start the new burst
first_on_this_day <- c()
for(i in 1:length(days)){
first_on_this_day <- min(tmp1[tmp==days[sel_int][i]])
sel_ext[which(tmp1==first_on_this_day)] <- T #mark on the
first observation on that day
}
return(sel_ext)
}
cltr2<-cutltraj(ltr1,"foo3(date)",nextr=F)
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Don Carlos
Gesendet: Samstag, 9. August 2014 13:09
An: [email protected]
Betreff: [R-sig-eco] segmenting (split) ltraj objects (adehabitatLT) into 10
day bursts
Dear list,
I have been trying to find a way to segment (split) ltraj into regular bursts
according to a temporal window (i.e. bursts containing 10 days of relocations).
The conceptual way I thought to implement this was to 1) extract the start date
and end date from the ltraj summary list for each burst (bursts have varying
start and end dates), 2) for each of these vectors create a sequence (seq)
using start and end dates and defining a 10 day interval, 3) use this to in
conjunction with cutltraj to cut ltraj into 10 day segments.
I have not succeed in implementing this but below a reproducible example taken
from the LT package and the steps as outlined. Any suggestions or pointers much
appreciated.
install.packages("adehabitatLT")
data(capreochiz)
ltr1<- as.ltraj(xy = capreochiz[,c("x","y")],
date = capreochiz$date,
id = "Roe.Deer", typeII = TRUE,
infolocs = capreochiz[,4:8])
sum<-summary(ltr1)
#extracting the min and max dates per burst (in this example #only one but
often many bursts per ltraj. Ideally bound.dates #should round date.start and
date.end up or down to the start of #the day and end of the day
bound.dates <- seq(min(sum$date.begin)-1,max(sum$date.end)+1,by="day")
#Below ideally what I would like to do but obviously not working
#as "bound.dates" not a logical expression. How could one #be constructed?
cltr1<-cutltraj(ltr1,"bound.dates",nextr=TRUE)
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