Cheers heaps Mike for your answer! I had projected my GPS points previously too and thought there was still something wrong... which was in my head really because I expected the wrong thing to happen. The code was working fine, my interpretation of the results, not so much! All good now! Thanks again, Elodie
Elodie CM Camprasse - PhD Candidate School of Life and Environmental Sciences Deakin University 221 Buwood Highway Burwood, Victoria 3125 Australia Email: [email protected] Mobile: (+61) 049 794 0793 ________________________________________ From: AniMov <[email protected]> on behalf of [email protected] <[email protected]> Sent: 25 October 2014 21:00 To: [email protected] Subject: AniMov Digest, Vol 104, Issue 12 Send AniMov mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of AniMov digest..." Today's Topics: 1. Grid size in MakegGridTopology - trip package (ELODIE CLAIRE MARIE CAMPRASSE) 2. Re: Grid size in MakegGridTopology - trip package (Michael Sumner) ---------------------------------------------------------------------- Message: 1 Date: Fri, 24 Oct 2014 20:26:04 +0000 From: ELODIE CLAIRE MARIE CAMPRASSE <[email protected]> To: "[email protected]" <[email protected]> Subject: [AniMov] Grid size in MakegGridTopology - trip package Message-ID: <[email protected]> Content-Type: text/plain; charset="utf-8" G'day everyone, I am trying to calculate time spent per grid fromages GPS data obtained on seabirds. I am confused about the MakeGridTopology function of the package trip. Instead of entering a number of cells with cells.dim, I would like to enter a distance - ie I want my grid to be of 50 by 50 m. I've tried playing with cells.dim and cellsize option but I am not managing to get what I need. Could anyone please clarify how to make such a grid? Cheers heaps! Elodie Sent from my Telstra Next G? device -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.faunalia.it/pipermail/animov/attachments/20141024/158584a1/attachment-0001.html> ------------------------------ Message: 2 Date: Sat, 25 Oct 2014 11:52:38 +1100 From: Michael Sumner <[email protected]> To: Animal Movement <[email protected]> Subject: Re: [AniMov] Grid size in MakegGridTopology - trip package Message-ID: <caacgz9-ty-cxkva5qbn-ltfvx7vpo+amcmnqmknotywqzot...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 Hello, you should provide the code you have tried and report what you expect versus what you get. But, I imagine the confusion probably comes from having data that is longitude / latitude and wanting a cell size in metres? For that you can use the adjust2longlat argument, which assumes units in kilometres. library(trip) example(trip) ## run example to get a dummy trip object makeGridTopology(tr, cellsize = c(50, 50) / 1000, adjust2longlat = TRUE) Does that help? The trip package is kind of a frozen snapshot from olden times, it should really be updated to use the raster package and make all this stuff far simpler and easier to understand. It used to drive me absolutely crazy trying to specify a grid using the maximally abstract GridTopology function, which is why I wrote "makeGridTopology". The raster package is much better at all of this, but still you have to know a bit about setting the right projection for you data and so on. One day I'll update this, but not many people ask about it - feel free to send suggestions/requests etc. Be aware that the cell size from makeGridTopology is a compromise to approximate a metres-based metric in long/lat - you should really choose a map projection and do analyses in that. Let us know if you want help with that. Cheers, Mike (author of trip). On Sat, Oct 25, 2014 at 7:26 AM, ELODIE CLAIRE MARIE CAMPRASSE <[email protected]> wrote: > G'day everyone, > I am trying to calculate time spent per grid fromages GPS data obtained on > seabirds. I am confused about the MakeGridTopology function of the package > trip. Instead of entering a number of cells with cells.dim, I would like to > enter a distance - ie I want my grid to be of 50 by 50 m. I've tried playing > with cells.dim and cellsize option but I am not managing to get what I need. > Could anyone please clarify how to make such a grid? Cheers heaps! > Elodie > > Sent from my Telstra Next G? device > > _______________________________________________ > AniMov mailing list > [email protected] > http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov > -- Michael Sumner Software and Database Engineer Australian Antarctic Division Hobart, Australia e-mail: [email protected] ------------------------------ Subject: Digest Footer _______________________________________________ AniMov mailing list [email protected] http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov ------------------------------ End of AniMov Digest, Vol 104, Issue 12 *************************************** _______________________________________________ AniMov mailing list [email protected] http://lists.faunalia.it/cgi-bin/mailman/listinfo/animov
