Thanks David, I'll investigate. Also, I've been thinking there's probably no real reason not to allow 2-location trips. ;)
Cheers, Mike 2010/9/30 Pinaud David <pin...@cebc.cnrs.fr>: > Hi Mike! > I've fixed my problem by running this (unelegant) code, with the same idea > as yours. I don't know if it's worth to include it in the trip package, but > here is the code! Feel free to adapt it and use it if you want. > I needed to change a little bit the trip class definition to convert a path > with two locations in a trip object. You set the limit at 3 locs when > defining a trip object, it makes sense that an interesting trip would have > more than 3 locs, but some colleagues here are working with dispersal of > individuals, calculating distance and bearing with 2 locs (birth / death or > birth/first reproduction place), so the package can be also usefull in this > case. > Thanks > David > > Le 09/09/2010 15:28, Michael Sumner a écrit : >> >> Sorry to have missed this. >> >> There's really no way to do this in longitude / latitude without a lot >> of manual handling. You could split into two trips, one using the >> eastern hemisphere, the other the western and use a shared [-180,180] >> grid that you sum together. >> >> What to do at the split coordinate depends on your actual data, there >> are many options. >> >> If you are still looking for an answer I could have a closer look at >> your example code, but real data would be more helpful if you can >> share it. There are a number of problems in the code you posted that >> prevent it from being easily run. >> >> Cheers, Mike. >> >> >> >> >> On Fri, Aug 6, 2010 at 8:10 PM, Pinaud David<pin...@cebc.cnrs.fr> wrote: >>> >>> Dear all, >>> I want to calculate a grid of time spent per cell with albatross data. >>> The >>> goal is then to relate this to fisheries data set on a 1x1° grid. >>> I use the trip package with tripGrid(), but have some problems with birds >>> crossing the date line. >>> Usually I use a projection to do that but here I need to keep the 1x1° >>> grid >>> in order to relate density tu some data (fisheries...). >>> I've tried with recenter() and nowrapSpatialLines(), without success. >>> Here a code: >>> >>> library(trip) >>> library(maps) # to draw world maps >>> >>> d<- data.frame(x=c(seq(50, 180, 10), seq(-170, 50, 10)), y=rnorm(n=37, >>> m=-50, sd=3), tms=Sys.time()-(37:1*60*60*24), id=rep(1, 37)) # an >>> example >>> coordinates(d)<- ~x+y >>> tr<- trip(d, c("tms", "id")) >>> proj4string(at)<- CRS("+proj=longlat +ellps=WGS84") >>> >>> map('world') >>> plot(tr, add=T) >>> points(coordinates(tr), t="l") >>> >>> # grid >>> grid.base<- expand.grid(Long=seq(-180, 180, by=1), Lat=seq(-70, -15, >>> by=1)) >>> # tab coords >>> coordinates(grid.base)<- ~ Long + Lat >>> proj4string(grid.base)<- CRS("+proj=longlat +ellps=WGS84") >>> gt<- makeGridTopology(grid.base, cellsize = c(1, 1)) # def grid topo >>> >>> # time spent per cell >>> tppc<- tripGrid(tr, grid = gt) >>> tppc01<- tppc # a copy for pres/abs >>> tpp...@data$z<- ifelse(t...@data$z> 0, 1, 0) >>> >>> image(tppc, col=rev(heat.colors(500))) # seems ok >>> map('world', add=T) >>> points(coordinates(tr), t="l") >>> >>> # but with presence/absence: >>> image(tppc01, col=c("white", "green")) >>> map('world', add=T) >>> points(coordinates(tr), t="l", col="blue") >>> >>> Some ideas ? >>> >>> >>> Many thanks for your time. >>> David >>> >>> -- >>> *************************************************** >>> David PINAUD >>> Ingénieur de Recherche "Analyses spatiales" >>> >>> Centre d'Etudes Biologiques de Chizé - CNRS UPR1934 >>> 79360 Villiers-en-Bois, France poste 485 >>> Tel: +33 (0)5.49.09.35.58 >>> Fax: +33 (0)5.49.09.65.26 >>> http://www.cebc.cnrs.fr/ >>> >>> *************************************************** >>> >>> >>> >>> >>> __________ Information from ESET Mail Security, version of virus >>> signature >>> database 5346 (20100806) __________ >>> >>> The message was checked by ESET Mail Security. >>> http://www.eset.com >>> >>> >>> _______________________________________________ >>> R-sig-ecology mailing list >>> R-sig-ecology@r-project.org >>> https://stat.ethz.ch/mailman/listinfo/r-sig-ecology >>> >>> >> >> > > -- > *************************************************** > David PINAUD > Ingénieur de Recherche "Analyses spatiales" > > Centre d'Etudes Biologiques de Chizé - CNRS UPR1934 > 79360 Villiers-en-Bois, France > poste 485 > Tel: +33 (0)5.49.09.35.58 > Fax: +33 (0)5.49.09.65.26 > http://www.cebc.cnrs.fr/ > > *************************************************** > > > > > __________ Information from ESET Mail Security, version of virus signature > database 5492 (20100930) __________ > > The message was checked by ESET Mail Security. > http://www.eset.com > > -- Michael Sumner Institute for Marine and Antarctic Studies, University of Tasmania Hobart, Australia e-mail: mdsum...@gmail.com _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology