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At present I have a dataset which is broken down by Electoral Divisions (circa 3,500). However, due to issues with some of my variables I need to choose a larger spatial unit - Local Electoral Area (LEA). An LEA is an aggregation of a number of different Electoral Divisions. The issue with the LEA shapefile, is the attribute table does not provide a lot of information of the region.

What I would like to do is aggregate my various Electoral Division variables to an LEA level. However, I believe this will be extremely difficult. Instead what I would like to do is join by ED's by LEA so I'll know what ED is in what LEA. The issue here is at present I have no identifier which is common between both shapefiles.

I originally was going to geocode by Electoral Divisions and than merge them to the LEA shapefile, however, 3,500 is quiet an amount, as well as ED names are quiet common with other areas in the world.

Is there some way to overlay the two shapefiles so my ED's are imbedded within the LEAs. Both shapefiles are working of the same coordinate system, so I imagine this is possible?

I'm using QGIS

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    what software are you planning on using? – Ian Turton Mar 11 '16 at 10:43
  • Have you tried using the Join attributes by location tool? – Joseph Mar 11 '16 at 10:46
  • How accurately has the spatial data been captured? I assume the shapefile contains polygons? Would I be possible to get a small sample? – PyMapr Mar 11 '16 at 10:55
  • @Joseph - When I try this all values appear "NULL". Both have the same coordinate reference system. – Sean O'C Mar 11 '16 at 10:56
  • @Thunderbolt - The shapefiles are available to download at cso.ie/en/census/census2011boundaryfiles I'm using Electoral Divisions and Local Electoral Areas. – Sean O'C Mar 11 '16 at 11:00
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The shapefiles you linked to should be resaved using the Save As... option and with another CRS such as:

EPSG: 2157, IRENEET95 / Irish Transverse Mercator

I tested this and resaved the shapefiles using "NEW_" as a prefix. I then used the Join attributes by location tool:

Join attributes by location

The output contains the attributes of both shapefiles with no NULL values (red box shows ED data; blue box shows LEA data):

Results

  • @SeanO'C - Most welcome buddy! Hope it works for you :) – Joseph Mar 11 '16 at 12:39

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