[R-sig-Geo] How to calculate the area of polygons with holes?

ld be some solutions, but since I am new to R, I need your help. Thanks in advance. Sincerely, Xin -- Lin Xin Department of Ecology, College of Urban and Environmental Sciences Peking University Beijing 100871, China Tel: +8610 62765578 Mobile: +86 15801416516 Email: linxin@gmail.com [[a

[R-sig-Geo] How to remove polygons according to their attributes?

Hi, everyone I have a shapefile with many adjacent polygons in. Each has a series of attributes such as ID and area. Now I want to remove some of them based on attributes, e.g. to remove polygons with areas less than a given value. How can I proceed? Thanks a lot.=) Lin Xin -- Lin Xin