[GIS] Symbolize a layer based on it’s related table (1:M relationship class)

Question

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.

Answer 1

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.