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/questions/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
Lat1,Long1 37.301283,-24.545717 37.324533,-24.599333 37.360867,-24.680267 37.368267,-24.6869 37.379067,-24.6914 37.399933,-24.723167 38.960567,-27.9429 38.90585,-27.875717 38.8109,-27.757067 38.755333,-27.695767
question loop2.R
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