https://community.esri.com/t5/geoprocessing-questions/calculate-field-by-dynamically-selected-records/m-p/1110996#M25924 <P>I am doing a project for a spatial statistics class that will test different quick "napkin math"&nbsp; 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.&nbsp;</P><P>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.</P><P>The only step I am troubled with is how calculate a field based only on selected features from another layer.&nbsp;</P><P>Thanks!&nbsp;</P> Mon, 25 Oct 2021 19:40:30 GMT ANDREWWhiteUSC 2021-10-25T19:40:30Z https://community.esri.com/t5/geoprocessing-questions/calculate-field-by-dynamically-selected-records/m-p/1110996#M25924 <P>I am doing a project for a spatial statistics class that will test different quick "napkin math"&nbsp; 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.&nbsp;</P><P>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.</P><P>The only step I am troubled with is how calculate a field based only on selected features from another layer.&nbsp;</P><P>Thanks!&nbsp;</P> Mon, 25 Oct 2021 19:40:30 GMT https://community.esri.com/t5/geoprocessing-questions/calculate-field-by-dynamically-selected-records/m-p/1110996#M25924 ANDREWWhiteUSC 2021-10-25T19:40:30Z https://community.esri.com/t5/geoprocessing-questions/calculate-field-by-dynamically-selected-records/m-p/1111030#M25925 <P><a href="https://community.esri.com/t5/user/viewprofilepage/user-id/428867">@ANDREWWhiteUSC</a>&nbsp;</P><P>Hello there.&nbsp; In order to calculate a field based on another feature you would have to join them, do the calculation, and then remove the join.</P> Mon, 25 Oct 2021 20:58:54 GMT https://community.esri.com/t5/geoprocessing-questions/calculate-field-by-dynamically-selected-records/m-p/1111030#M25925 ABishop 2021-10-25T20:58:54Z