Thanks a lot for your advice, we managed to solve the problem by interpolating a redundant point!
All the best, Patricia -----Opprinnelig melding----- Fra: AniMov [mailto:animov-boun...@faunalia.it] På vegne av Calenge Clement Sendt: 9. oktober 2014 15:42 Til: Animal Movement Emne: Re: [AniMov] R package ADEhabitatLT - function ltraj/cutltraj - bursts On 09/10/2014 15:36, Michael Sumner wrote: > Would it not be ok to just interpolate a redundant point between the > two? Then you don't fall foul of the rules? yes, that would be a better solution (no need to edit the function then). All the best, Clément > > That seems safer and more reproducible than moving the ground under your feet? > > (Just my 2 cents having not tested either path). > > Cheers, Mike. > > On Thu, Oct 9, 2014 at 9:57 PM, Calenge Clement > <clement.cale...@oncfs.gouv.fr> wrote: >> >>> I have a question concerning the ADEhabitatLT package in R. We are >>> analyzing GPS data of beavers sampled at an 15 min interval from approx. >>> 7 pm - 7 am for 7 nights. The aim of our study is to look at >>> changes in movement behavior after capture (we tag them with GPS >>> units and release them afterwards). >>> >>> We used the ltraj function to create an ltraj object with bursts for >>> every individual. We then divided the bursts into sub-bursts for >>> every night with cutltraj by using time lags over 8 hrs (when >>> beavers are inside the lodge during daytime) for splitting up. >>> However, we get a warning message saying that >>> >>> Warning message: >>> >>> In cutltraj(Beav, "foo(dt)", nextr = TRUE) : >>> >>> At least 3 relocations are needed for a burst >>> >>> 9 relocations have been deleted >>> >>> For our purpose, the first night after capture is really important. >>> And just for this night, we sometimes only got 2 relocations since >>> the animals went into their lodge (no GPS signal), meaning that the >>> function just deletes the first night for some of our animals. We >>> thus would like to include these bursts for analysis and wonder >>> whether there is a possibility to create a burst with only 2 relocations? >> >> Some of the statistics used to describe the trajectory require at >> least two steps, i.e. 3 relocations (e.g. the relative angle, or >> turning angles, between successive steps). However, if you insist, >> you can edit the function cutltraj, e.g. using the command: >> >> cultraj<-edit(cutltraj) >> >> and delete the following commands at the end of the function: >> >> resb <- res[rrr >= 3] >> if (length(res) != length(resb)) >> warning(paste("At least 3 relocations are needed for a burst\n", >> sum(rrr[rrr < 3]), "relocations have been deleted")) >> >> This will avoid this unwanted behaviour. However, I cannot guarantee >> that the other functions in adehabitatLT will work with a >> 2-relocations ltraj (Two relocations do not define a trajectory; you >> need at least three). You are on your own if you decide to do that! >> >> HTH, >> >> Clément Calenge >> -- >> Clément CALENGE >> Cellule d'appui à l'analyse de données Direction des Etudes et de la >> Recherche Office national de la chasse et de la faune sauvage Saint >> Benoist - 78610 Auffargis tel. (33) 01.30.46.54.14 >> _______________________________________________ >> AniMov mailing list >> AniMov@faunalia.it >> http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov > > > -- Clément CALENGE Cellule d'appui à l'analyse de données Direction des Etudes et de la Recherche Office national de la chasse et de la faune sauvage Saint Benoist - 78610 Auffargis tel. (33) 01.30.46.54.14 _______________________________________________ AniMov mailing list AniMov@faunalia.it http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov _______________________________________________ AniMov mailing list AniMov@faunalia.it http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov
