Method for: Creating contour maps of geocoded point shapefile attributes
Hello: If one has a polygon shapefile of the USA and a point shapefile of USA cities (both in geographic coordinates), and the point shapefile includes demographic attributes for each city, what would be the best way to create a contour map of one of the attributes that overlays the polygon map? I have been experimenting with using akima.interp (to generate a grid of interpolated values) and contour (to generate the contours), with mixed results. I think that I can work out a technique to get this done, but would like to know if this capability is embedded in any of the R spatial classes. Thanks for any insight into this! Rick Reeves -------------- next part -------------- A non-text attachment was scrubbed... Name: reeves.vcf Type: text/x-vcard Size: 339 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20071129/4d010230/attachment.vcf>