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I am having 15 polygon shape files of a sub locality of a city that is having address in their attribute table. I want to merge these polygons based on the address in the attribute table?how can i do this in Qgis. I also attempted vector...>>>data management tools...>>>>merge shape files to one.But it is giving me the combined polygon but when I look into the attribute table the values shows me null? What is the problem behind it?

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QGis's fTool's dissolve tool did not work for me, so I'm solving this on rails :)

Now this solution might not be good for some, because you have to load in every parcel into a database, but I had already done that so it worked for me.

Here's my pseudo code, I haven't run anything yet

Polygon.all.each do |p|
  if check_if_superpolygon_exists(p)
    if check_if_contiguous_superpolygon_exists(p)
      add_to_contiguous_superpolygon(p)
    else
      create_new_superpolygon(p)
    end
  else
    create_new_superpolygon(p)
  end
 end

check_if_contiguous_superpolygon_exists will use ST_Intersects & the others will just check if records exist with the same attribute-value and stuff. The only tricky part I haven't done yet is merging a new polygon into the superpolygon's spatial data.

  • this code didn't actually work for me – boulder_ruby Jul 9 '15 at 1:23

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