In un messaggio del Thursday 02 July 2009, Roland Kays ha scritto: > Hi, I'm working on some GPS data at 15min intervals. I'd like to take any > consecutive locations that are closer than GPS error (say 25m) and average > them together to get one location for all time steps. For example, when an > animal is resting in a tree for an hour the locations might still bounce > around due to GPS error. > > I just ran through the adehabitat trajectory tools and didn't see anything > in there - any other suggestions? thanks
Two suggestions:
1) given that you have GPS data, a first solution could be to process
incrementally time-adjacent fixes (say, in a while loop) and once a given
threshold is reached (e.g. all the points examined are well under 15 m, or all
the point fall insida a reasonably small time slot, or both...) do the
averaging.
I'm using such an approach (the while loop point accumulator, I mean) to
preprocess data for a triangulation module we're deveolping here, if you want
to have a peek at the code, you can access the svn repository at
svn://home.prea.net/svn/triang/trunk
2) adehabitat ltraj class can be used to do some trajectory resampling: if
you've managed to convert your data into a ltraj it should be easy to extract
(resampling) some already averaged pseudo-locations
As you can see, I'm strongly biased towards R at present... like Python, it
just works (and you _can_ go back to Pytho+Rpy to build some QGis interfaces).
HTH
--
"I will make no bargains with terrorist hardware."
-- Peter da Silva
-----------------------------------------------------------
Damiano G. Preatoni, PhD
Unità di Analisi e Gestione delle Risorse Ambientali
Dipartimento Ambiente-Salute-Sicurezza
Università degli Studi dell'Insubria
Via J.H. Dunant, 3 - 21100 Varese (ITALY)
tel +39 0332421538 fax +39 0332421446
http://biocenosi.dipbsf.uninsubria.it/
ICQ: 78690321 jabber: p...@jabber.org skype: prea.net
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