[R-sig-Geo] SpatialLines from SpatialLinesDataFrame

[Roger Bivand]

On Mon, 9 Jul 2012, Lyolya wrote:

> Dear List,
>
> I am trying to create a map for a SpatialPointsDataFrame object (package
> sp), and I want to use some lines as a layout for my plot. I use the
> function spplot and its argument sp.layout for the purpose. The point is, I
> cannot figure out how to retrieve a SpatialLines object from a
> SpatialLinesDataFrame that I got. I.e, I try to do the following:
>
> #points_object - a SpatialPointsDataFrame
> #lines_object - a SpatialLines object
> #lines_data_frame - a SpatialLinesDataFrame
>
> spplot(points_object, cuts, sp.layout=list("sp.lines", lines_object), main)
>
> and the problem is that I don't know how to derive the lines_object from
> the lines_data_frame. I have already tried the options:
>
> lines_object <- as.SpatialLines.SLDF(lines_data_frame)

Where did you get that from? These are all S4 classes, so the coercion 
method is:

as(lines_data_frame, "SpatialLines")

However, you probably do not need to do anything, as the sp.layout 
"sp.lines" function takes objects which can be coerced to SpatialLines, 
including SpatialLinesDataFrame.

Roger

>
> and
>
> p.layout=list("sp.lines", lines_data_frame at lines)
>
> but none of these works for the plot.
>
> Could you please indicate me how I could make it work?
>
>

-- 
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no