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</o:shapelayout></xml><![endif]--></head><body lang=DE link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>Hello list,<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>I have a question about dealing with duplicate polygons (dp) coming into GRASS from a polygon shapefile. The polygons are not overlapping or having gaps, but there are a number of real duplicate ones (polygons show parcels with owners, and if one parcel has two or more owners, e. g. wife and husband, this situation in the shapefile is represented by two identical polys with two database rows that only differ in the owners name).<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>My goal is to get rid of duplicates, having a result with only one polygon/centroid at a given location with only one owner name. The name does not matter, it can be chosen arbitrary by the system. This works fine when using ESRI "clean"-command. The structure of the database table is maintained while one (or many) of the dp is/are lost, leaving only one valid polygon.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>Now, I found an older thread called "unable to get rid of duplicate polygons". Obviously, the problem/question is the same but I could not find a solution for GRASS there. So I tried:<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:35.4pt;text-indent:35.4pt'><span style='font-family:"Verdana",sans-serif'>v.clean -c input=input@mapset output=output_clean tool=snap,rmdac,bpol threshold=0.01,0,0<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>and<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:35.4pt;text-indent:35.4pt'><span style='font-family:"Verdana",sans-serif'>v.clean -c input=input@mapset output=output_clean tool=break,snap,rmdupl,rmdac,bpol<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>Nothing did work. I get a map with tree layers, one showing the islands only (layer 0), one showing the complete polygon set with duplicates (1), and one showing only the duplicates (2). I also tried to delete layer 2, assuming that this might remove the dp, but it only messed up the dataset.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>What am I doing wrong?<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'>Regards, Uwe<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Verdana",sans-serif'><o:p> </o:p></span></p></div></body></html>