[R-sig-Geo] shortestPath in a loop

[Roland Harhoff]

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
> > >>
> > >
> > >
> >
> >         [[alternative HTML version deleted]]
> >
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> >



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> Jérôme Mathieu <http://www.jerome-mathieu.com/>
> Université Pierre & Marie Curie <http://www.upmc.fr/>
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