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I am new to GIS and hope this is not too basic. I am using QGIS.

Say I have two shapefiles: SHP1, with attributes allocated to municipalities, and another shapefile I built from a wkt file, SHP2, which is an orthogonal 60 by 60 grid.

I wish to do the following: add an attribute column to SHP which reflects the weighted average of an attribute from the underlying SHP1.

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  • Will your column have the same weighted value for each row? Also, is there a common attribute between the shapefiles you can use to join them? Or were you hoping to do a spatial join where the connection is location, rather than attributes?
    – Baltok
    Commented Feb 6, 2013 at 19:29
  • you speak of weighted average. Weighted by what? Do you already calculated this attribute?
    – Curlew
    Commented Feb 6, 2013 at 19:31
  • hello, the average for each cell should be an attrabitue from the underlying shapefile, weighted by the respective area of each attribute present in the cell. Commented Feb 8, 2013 at 10:01
  • An image might be more likely to better explain what I intend to do: s7.postimage.org/44ji3ya5n/grelha.jpg Purple lines delimitate municipalities. Each municipality has an attribute (a real number). What I wish to do is to get the value of that attribute with the space definition of the green grid. For a cell over only one municipality, it will be the value from that municipality. For a cell lying over parcels of different municipalities, the value shall be an average of the underliying municipalities, weighted by the respective municipalities areas. I hope I can get help. Many thanks. Commented Feb 8, 2013 at 15:49

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