Error-message-when-trying-to-compute-the-least-cost-path-in-gdistance-in-R

Marta,

I don't know what constructed your trCost (1560 x 1560 sparse Matrix of
class "dsCMatrix") which I take to be symmetric of
8 directions.

r <- raster(nrows = 1560, ncols = 1560)
r <- setValues(r, runif(ncell(r)))
trCost <- transition(r, transitionFunction = mean, directions = 8)

All I can find to the moment is a little problem of naming in the
shortestPath function call

i.e. pts1 and pts2 are matrix objects (like coordinates), presumably to be
start and goal.

and if they are written as:

plot(shortestPath(trCost, pts1[1,], pts2[1,], output="SpatialLines"))
you get a plot
# without add=TRUE in my case as
# with add=TRUE it reminds me I haven't called plot yet hence nothing to
add to:
Error in plot.xy(xy.coords(x, y), type = type, ...) :
  plot.new has not been called yet


rather than:

plot(shortestPath(trCost, pts[1,], pts[2,], output="SpatialLines"))
which gives this error:

Error in shortestPath(tr, pts[1, ], pts[2, ], output = "SpatialLines") :
  object 'pts' not found


So I imagine that isn't what you had in your call


the Error, generally otherwise would point to NA(s) in the matrix (trCost).
Well. I'm guessing.

HTH,

Chris

http://r-sig-geo.2731867.n2.nabble.com/Error-message-when-
trying-to-compute-the-least-cost-path-in-gdistance-in-R-tt7590273.html

Hi everyone,

I have a similar problem. I have two points that I want to join in one line
"SpatialLines"

class(trCost)#"TransitionLayer"+attr gdistance
summary(trCost)#1560 x 1560 sparse Matrix of class "dsCMatrix", with 8
entries

pts1<-cbind(x=-27.54572,y=38.30128)

pts2<-cbind(x=-28.59933,y=37.32453)
#
class(pts1)#matrix
class(pts2)#matrix
#
is.numeric(pts1)#[1] TRUE

plot(shortestPath(trCost, pts[1,], pts[2,], output="SpatialLines"),
add=TRUE)
Error in if (is.numeric(v) && any(v < 0)) { :
  missing value where TRUE/FALSE needed

Thanks in advance

Marta

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