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)

and

p.layout=list("sp.lines", lines_data_frame@lines)

but none of these works for the plot.

Could you please indicate me how I could make it work?

-- 
Thanks in advance,
Lyolya.

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