[R-sig-Geo] How to extract part of Map object using maptools

Edzer J. Pebesma e.pebesma at geog.uu.nl
Thu Nov 20 15:21:47 CET 2003

Roger Bivand wrote:

>How should 
>the bounding box be handled, should it be left as is, or reduced to suit 
>the subset?
This is (more or less) a question about interfacing. I'd suggest to modify
the bounding box such that it suits the subset. First I thought about a
way to expand it, as in

bbox(europe) <- bbox(world)

but the more I think about it, the less I like it: expanded bounding boxes
do not describe the data in the object, and probably are only of use to
extend the plotting area -- a trick. For that purpose we'd better pass a
bbox to generic plotting functions, as in

plot(europe, bbox=bbox(world))

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