Re: [GRASS-user] ... getting rid of duplicate polygons ...
On Fri, Feb 10, 2017 at 5:44 PM, Uwe Fischerwrote: > > Hello list, > > 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). > > 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. > > 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. There is no tool in GRASS that automatically removes all but one category values from a feature. You would need to use the vector digitizer or v.edit. Alternatively, you could create a copy of the vector, remove all categories from layer 1 and 2 with v.category type=centroid option=del cat=-1 layer=1 and v.category type=centroid option=del cat=-1 layer=2 Then assign new categories with v.category type=centroid option=add cat=1 layer=1 Finally try v.distance from= to= from_type=centroid from_layer=1 to_type=centroid to_layer=1 upload=to_attr to_column= column= Markus M > So I tried: > > v.clean -c input=input@mapset output=output_clean tool=snap,rmdac,bpol threshold=0.01,0,0 > > and > > v.clean -c input=input@mapset output=output_clean tool=break,snap,rmdupl,rmdac,bpol > > 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. > > > > What am I doing wrong? > > > > Regards, Uwe > > > > > ___ > grass-user mailing list > grass-user@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/grass-user ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] ... getting rid of duplicate polygons ...
Uwe, It wouldn't be easy to tell what your problem is without seeing your dataset. If you don't want to share your dataset, maybe create a small subset of it so others can try it. Regards, Huidae On Fri, Feb 10, 2017 at 11:44 AM, Uwe Fischerwrote: > Hello list, > > > > 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). > > > > 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. > > > > 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: > > > > v.clean -c input=input@mapset output=output_clean tool=snap,rmdac,bpol > threshold=0.01,0,0 > > > > and > > > > v.clean -c input=input@mapset output=output_clean > tool=break,snap,rmdupl,rmdac,bpol > > > > 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. > > > > What am I doing wrong? > > > > Regards, Uwe > > > > ___ > grass-user mailing list > grass-user@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/grass-user > ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] ... getting rid of duplicate polygons ...
Hello list, 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). 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. 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: v.clean -c input=input@mapset output=output_clean tool=snap,rmdac,bpol threshold=0.01,0,0 and v.clean -c input=input@mapset output=output_clean tool=break,snap,rmdupl,rmdac,bpol 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. What am I doing wrong? Regards, Uwe ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] ... getting rid of duplicate polygons ...
Hello list, 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). 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. 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: v.clean -c input=input@mapset output=output_clean tool=snap,rmdac,bpol threshold=0.01,0,0 and v.clean -c input=input@mapset output=output_clean tool=break,snap,rmdupl,rmdac,bpol 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. What am I doing wrong? Regards, Uwe ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user