Calculate Field by Dynamically Selected records

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10-25-2021 12:40 PM
ANDREWWhiteUSC
New Contributor

I am doing a project for a spatial statistics class that will test different quick "napkin math"  aggregation methods (Select features that intersect, Select features that have their center in, etc) to see how well they correlate to the EPA's Dasymetric Toolbox's population estimations for HUC-12 Watersheds. 

In a model, I am hoping to select watersheds one at a time, select intersecting census tracts (or one of the other selection techniques), and calculate the population field based on the sum of the selected census tract's populations before moving to the next watershed. Ideally this results in a table where each watershed has a population value for each aggregation method in a different column.

The only step I am troubled with is how calculate a field based only on selected features from another layer. 

Thanks! 

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ABishop
Regular Contributor

@ANDREWWhiteUSC 

Hello there.  In order to calculate a field based on another feature you would have to join them, do the calculation, and then remove the join.

Amanda Bishop, GISP
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