[R-sig-Geo] shortestPath in a loop

Mon Jan 16 11:45:00 CET 2017

Hi Jerome,

There are several R packages to join points. However, I have two relevant
issues with them.
 -The first,  I need to get the "Lines" from these tracks in "spatial
Lines". For example, in the adehabitatLT package you can get easily the
trajectories of the animal but with the class " ltraj". I don't know
   how transform this object class into spatial lines.
-The second, when I made the tracks I need to avoid the coast, and I don't
know how do that in adehabitatLT.

Any idea?

Thanks for your suggestions,

Marta

2017-01-14 15:21 GMT-01:00 Roland Harhoff <roland.harhoff at uni-muenster.de>:

> Hi Marta,
>
> and did you check the trajectories package ...?
>
> https://cran.r-project.org/web/packages/trajectories/index.html
>
> Cheers!
> Roland
>
>
> Jérome Mathieu schrieb am 2017-01-14:
> > Hi,
>
> > Did you have a look at the package adehabitatLT?
>
> > https://cran.r-project.org/web/packages/adehabitatLT/
> vignettes/adehabitatLT.pdf
>
> > It deals with trajectories based on points ordered by date.
>
> > Jerome
>
>
> > 2017-01-13 11:41 GMT+01:00 marta azores <martazores at gmail.com>:
>
> > > Thanks for your quick reply to my question,
> > >
> > > This ten points are ordered by time (date + time), and I know ,the
> points
> > > are all connected.  I didn't include the column with the time in this
> > > example, to make it simple.
> > >
> > > After read your messages, I was looking the minimum spanning tree for
> the
> > > vertices.
> > > The advantage with the function "shortestPath" is that you have as
> result a
> > > spatial line output, which I need it.
> > > However, the minimum spanning tree give as output an ordiplot.
> > >
> > > Is it possible to transform the ordiplot into spatialLines?
> > >
> > > Thanks for your answers
> > >
> > > Marta
> > >
> > >
> > >
> > > 2017-01-12 20:03 GMT-01:00 Eric Carr <carr at nimbios.org>:
> > >
> > > > Generically independent of R, A graph and the connectivity between
> points
> > > > needs defined before a shortest path algorithm can be applied.  If it
> > > > assumes all points are connected, than the shortest path will be a
> > > straight
> > > > line.  What you are looking for is some sort of  minimum spanning
> tree
> > > for
> > > > the vertices.
> > > > Eric
> > > >
> > > > On Thu, Jan 12, 2017 at 11:17 AM, marta azores <martazores at gmail.com
> >
> > > > wrote:
> > > >
> > > >> Dear forum members,
> > > >>
> > > >> I would like to know how join several points with the aim to track a
> > > ship.
> > > >>
> > > >> After reading the documentation of some packages, I decided to use
> the
> > > >> function shortestPath, but I only got the line between the first
> and the
> > > >> last location of my points list. I need the complete survey,
> including
> > > also
> > > >> the middle points. I try a loop to build the survey of the boats
> using
> > > >> their locations, but It didn't work to me.
> > > >>
> > > >>
> > > >> Any idea?
> > > >>
> > > >> Thanks in advance,
> > > >>
> > > >> Marta
> > > >>
> > > >> #script# it's also attached in a R.file: question loop2.R
> > > >> ##########################################################
> > > >> #
> > > >> #raster# it's attached
> > > >> azoTS1<- raster("C:/Users/Documents/azoTS1.tif")#wgs84
> > > >> #
> > > >> #10 points# it's attached
> > > >> boat <- read.table("C:/Users/Documents/10pontos.csv", header=TRUE,
> > > >> sep=",", na.strings="NA", dec=".", strip.white=TRUE)#
> > > >> head(boat)
> > > >>
> > > >> #raster to transitionlayer
> > > >> trCostS4<- transition(1/azoTS1, mean, directions=4)
> > > >>
> > > >> # points to spatialpointsdataframe
> > > >> x=boat$Long1
> > > >> y=boat$Lat1
> > > >> coords = cbind(x, y)
> > > >> plot(coords)
> > > >> sp = SpatialPoints(coords, proj4string=CRS("+proj=longlat
> +ellps=WGS84
> > > >> +datum=WGS84"), bbox = NULL)
> > > >> sp
> > > >> spdf=SpatialPointsDataFrame(sp,boat)
> > > >> spdf
> > > >> nrow(spdf)
> > > >> plot(sp,axes=TRUE)
> > > >> plot(spdf,add=TRUE, axes=TRUE)
> > > >>
> > > >> #shortestpath
> > > >>
> > > >> ## 1) this script only join the first point of the list and the last
> > > one,
> > > >> and the points in the middle are not used.
> > > >> CostpathSPdf <- shortestPath(trCostS4, spdf[1,], spdf[10,],
> > > >> output="SpatialLines")
> > > >> plot(CostpathSPdf,add=TRUE,axes=TRUE,col=2)#R_plot1.png (it's
> attached)
> > > >>
> > > >> ## 2) this script didn't work to me
> > > >>
> > > >> #first way from website: http://stackoverflow.com/quest
> > > >> ions/8127066/loop-or-sapply-function-for-multiple-least-
> > > >> cost-analysis-in-r?answertab=active#tab-top
> > > >> for(i in 1:nrow(spdf)) {
> > > >>   # Computation
> > > >>   Costpath <- shortestPath(trCostS4, spdf[i,], spdf[10,],
> > > >> output="SpatialLines")
> > > >>   plot(Costpath)
> > > >>
> > > >> }
> > > >>
> > > >> #Error in validObject(.Object) :
> > > >> #invalid class “SpatialLines” object: bbox should never contain
> infinite
> > > >> values
> > > >>
> > > >> _______________________________________________
> > > >> R-sig-Geo mailing list
> > > >> R-sig-Geo at r-project.org
> > > >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> > > >>
> > > >
> > > >
> > >
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> > >
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> > >
>
>
>
> > --
> > Jérôme Mathieu <http://www.jerome-mathieu.com/>
> > Université Pierre & Marie Curie <http://www.upmc.fr/>
> > Institute of Ecology and Environmental Science (Paris)
> > <https://ieesparis.ufr918.upmc.fr/>
> > Team EERI
>
> > 4 place Jussieu
> > Tour 44-45, 5th floor, door 514
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>
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>
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