On Thu, 9 Feb 2006, Tarmo Remmel wrote:
Dear List, I have examined the sp, maptools, and shapefiles packages (Windows) but cannot seem to figure out a solution for writing shapefiles for 'curvy shapes'. The scenario is that I generate a series of polygons, circles, and ellipses on a plot and would like to convert them to shapefiles. Since the circles and ellipses are do not return a coordinate list during the plotting sequence (e.g., all I need supply are the lengths of axes and rotation angle), is there an easy way by which the plot window can be converted to a shapefile?
No, the plot window is committed to the device, and (re)-capturing the objects there as polygon objects will be messy. You'll need to generate an object that can be drawn as a sequence of straight line segments, and create a polygon object from that, from the x,y coordinates of the centre and the radius, or major/minor axes lengths and orientations. There is some code on: http://finzi.psych.upenn.edu/R/Rhelp02a/archive/56190.html (see RSiteSearch("circle")) but I don't know if it will suit your purposes. Once constructed, the polygons can be built into an object for exporting.
Thank you, Tarmo
__________________________________________ Tarmo Remmel Ph.D. GUESS Lab, Department of Geography University of Toronto at Mississauga Mississauga, Ontario, L5L 1C6 Tel: 905-569-4382 Lab: 905-828-3868 Fax: 905-828-5273 Skype: tarmoremmel http://eratos.erin.utoronto.ca/remmelt ______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
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