Error in retainedges[dat$seg] : invalid subscript type 'list'

Question

I am conducting linearK function for the observed point pattern on a linear network and I get the following error Error in retainedges[dat$seg] : invalid subscript type 'list' I do not understand what it means and how should I correct it.

On the traceback call, I get the following information

> traceback()
4: thinNetwork(x, retainvertices = subi)
3: countends(L, X[-j], D[-j, j], toler = toler)
2: linearKengine(X, r = r, ..., denom = denom, correction = correction, 
       ratio = ratio)
1: linearK(sl2)

Could someone help me on what this error means and how I can correct it.

Thank you.

Answer 1

Your network is a bit problematic since it is disconnected. It has one very big component with 3755 vertices and 5593 lines and then 5 small components with only 2 or 3 vertices and 1 or 2 lines that are not connected to anything else. In your example you have only two points in this big network (both occurring in the big component as far as I can tell). We might be able to handle this in future versions of spatstat, but for now I suggest you simply discard the small empty components. Then I think linearK works as expected for your example (although I doubt you find interesting information from a pattern of 2 points!).

To identify connected components of a linear network use connected.linnet with argument what = "components" then you get a list of connected components and you can use the big connected component to define a new lpp on a connected linnet. With your example you could do something like (noting that component number 1 is the main component):

comp <- connected(as.linnet(sl2), what = "comp")
sl2new <- lpp(as.ppp(sl2), comp[[1]])