Looping over spatial data

Sorry for what may be a simple question. I am having an issue looping over 
spatial data. Here is the code:

usa.map = read.shape(file.choose()) #Shape file of the US, 51 records
There is a reason for read.shape() saying that it is deprecated. Please 
use classes defined in the sp package, and methods to read them, here 
possiblt readShapeSpatial() in maptools.
pt = data.frame(x=-73.793, y=42.857)
If pt is a SpatialPoints object, you just use an overlay() method.
shapes = Map2poly(usa.map)
shape = shapes[[35]] #This is New York

pip(pt, shape) #This works, returns the point as I expect since it is within 
NY

for(i in 1:length(shapes)) {
	shape = shapes[[i]]
	pip(pt, shape)
	#This is where the error occurs
}

This is the error I get:

Error in inout(pt, shape) : NA/NaN/Inf in foreign function call (arg 4).

Almost certainly your assumption that the shape is a single ring is not 
met for some i, leading the splancs functions you are using to fail. Use 
sp classes, they are there to help.

Roger
Thanks for any help.

-Jason

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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, 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

Looping over spatial data

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