Zilefac Elvis <zilefacelvis <at> yahoo.com> writes:
>
> Hello,
>
> I have two spatial map objects (reproducible example further down)
> which I would like to overlay in R. The
> ESRI shapefiles were read using:
>
The reproduction of the data didn't work with dput().
> library(rgdal)
> Prairie.Boundaries <- readOGR(".", "boundaries")
> watersheds<-readOGR(".","watersheds")
>
> The two objects have same projection:
> print(proj4string(watersheds))
> [1] "+proj=longlat +datum=NAD83 +no_defs +ellps=GRS80 +towgs84=0,0,0"
>
> print(proj4string(Prairie.Boundaries))
> [1] "+proj=longlat +datum=NAD83 +no_defs +ellps=GRS80 +towgs84=0,0,0"
>
> However, the spatial limits are different:
This is not an intrinsic problem.
> Problem:
> How can I overlay "watersheds" on "Prairie.Boundaries"?
>
> For example:
>
> plot(Prairie.Boundaries, axes=TRUE, border="black")
> plot(watersheds,border="gray8",col="white",axes=TRUE)
I do not see add=TRUE here, so the second plot() erases the first. If you
are trying to overplot Prairie.Boundaries with filled watersheds polygons,
the Prairie.Boundaries will be covered anyway with col="white".
What happens with:
plot(watersheds, border="gray8", col="white", axes=TRUE)
plot(Prairie.Boundaries, add=TRUE)
Consider posting questions of this kind on R-sig-geo, this list is for
general R help.
Do try to grasp what you are trying to do first, before asking for help.
Also check that reproducible examples actually reproduce.
>
> I tried to extend the ylim and xlim of "Prairie.Boundaries" to match
> those of "watersheds" but could not
> display the shapefiles on same plot.
>
> Please help.
> Thanks, Asong.
>
>
#--------------------------------------------------------------
>
> dput(watersheds)
> new("SpatialPolygonsDataFrame"
>
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