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I have a layer of polygons joined by a relationship class to a table by Field = DistrictIDNumber

The Table has multiple entries for each polygon so it is a one to many relationship.

Is there any way to symbolize the polygons based on count of related entries? Lets say they are number of observations and the polygons are districts within a county. Can I symbolize the polygons, in graduated colors, based on the number of observations reported in that district?

I can't use the actual point data of the table.

I'm currently using ArcGIS 10.2 but have access to R, if you guys think this would be a more appropriate application.

  • 3
    You have to do summary on related table and transfer result to parent. Arcgis – FelixIP May 5 '16 at 20:18
  • Did you try using Summary Statistics to create a table that flattens the one-to-many into a count that you can just join and symbolize? – PolyGeo Jun 30 '16 at 10:07
  • You can try to create a pivot table from the actual table and relate the polygon layer to this pivot table already containing the count data.Or you can try to Dissolve (Data Management toolbox, Generalization toolset) where you can use DistrictIDNumber as Dissolve Field and Statistcs Field with Count Statistic type. – Zsott Jul 1 '16 at 9:46
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I would use the Summary Statistics tool to create a table from the related table that flattens the one-to-many into a count that you can just join and symbolize.

Summary Statistics:

Calculates summary statistics for field(s) in a table ... A field will be created for each statistic type using the following naming convention: SUM_, MAX_, MIN_, RANGE_, STD_, FIRST_, LAST_, COUNT_ (where is the name of the input field for which the statistic is computed) ... If a Case field is specified, statistics will be calculated separately for each unique attribute value.

  • 2
    This seems static. What if the data changes? Then you have to do it again each time someone adds or removes data to the related dataset. – awe Jan 18 '17 at 9:46
  • I have not claimed this to be a dynamic solution. – PolyGeo Jan 18 '17 at 9:51
  • Fair enough. I just want to point it out, in case the OP needs it to be dynamic. – awe Jan 18 '17 at 10:15

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