Hi Steven,

You should check the projections of your datasets (summary()).

When I do the same kind of analyses, I use:

readOGR(), to read the shp
proj4string(), to assign a projection
overlay(), to make spatial overlay analysis
spplot(), to plot more than one spatial layer

hope this help

Sam


On Tue, Apr 9, 2013 at 9:10 AM, Steven Ranney <steven.ranney@gmail.com>wrote:

> All -
>
> My apologies for what is likely a neophyte questions but I'm new to spatial
> plotting in R and to .shp files in general.  I don't know all the
> terminology which makes reading the help files that much more difficult.
>
> I've been asked to do a "point.in.polygon" analysis of some dolphin
> resighting data.  I have recapture coordinates for these sightings and can
> convert them into SpatialPoints() objects.  I have a .shp file (along with
> all of the ancillary files that go with a .shp: .prj, .dbf, .sbn, .sbx,
> .shx, .xml) with three different polygons.  I read in the .shp file with
> readShapePoly().  I can plot the .shp and the coordinates independently but
> when I ask for an over() of the coordinates and polygons, I get "NA" for
> each of my resighting events.
>
> I'm sure my inability to do what I thought was a simply analyses has to do
> with my lack of familiarity with the spatial side of R.  Can anyone give me
> a hand with this?  I'd like to be able to share data but unfortunately it's
> rather sensitive and will be part of a litigation.
>
> Thanks in advance for your assistance.
>
> SR
> Steven H. Ranney
>
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