topic Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within in Geoprocessing Questions

Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 14:22:48 GMT

I am trying to iterate through a set of polygons and for each polygon select the points in another feature class which fall within. Once those points are selected I want sum the values of one of the point attributes and add that sum to an attribute field in the polygon. Everything seems to work except if no point falls within the polygon instead of 0 the field in the polygon attribute is filling to 1. I have tried various preconditions and the field value Null is set to 0 but this keeps occurring. Attached is a copy of the current model.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 15:17:08 GMT

Can you not achieve the same without a model and use a Spatial Join, with a field mapping merge rule set to 'SUM' of that particular field?

Spatial Join (Analysis)—ArcGIS Pro | Documentation

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 15:23:57 GMT

I'm looking to total an attribute field in the selected point feature class which has a count number in it, so not just summing the number of points that fall within the polygon. For instance there may be two points within the polygon, one with a count of 1 and one with a count of 3. I want to fill in the polygon attribute with the value of 4. This model successfully does that but when there are no points within the polygon it is filling in the attribute field as 1 instead of 0.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 15:31:00 GMT

Yes, you can control how a field is mapped in the spatial join. As you say, the default would be to return a JOIN_COUNT, JOIN_FID etc. and the other fields you have specified in the field mapping.

Of those other fields, you would have the attribute of the first coincident point found, BUT you can control how this is done.

Look at the field map parameter in the tool, and the merge rule dropdown.

from the link I supplied:

Merge rules specified in the Field Map of Join Features parameter only apply to attributes from the join features and when more than one feature is matched to a target feature (when Join_Count > 1). For example, if three features with DEPTH attribute values of 15.5, 2.5, and 3.3 are joined, and a merge rule of Mean is applied, the output field will have a value of 6.1. Null values in join fields are ignored for statistic calculation. For example, 15.5, <null>, and 2.5 will result in 9.0 for Mean and 2 for Count.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 16:02:08 GMT

I see what you mean, so:

Target Features: Polygon

Join Features: Point

Output fields: Polygon attribute field selected

Source: Merge Rule=Sum, Point attribute field to sum selected

This configuration gives me all NULL values in the polygon field.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 16:13:10 GMT

can you screenshot the tool parameters and the output?

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 16:16:36 GMT

TOT_GS is the field I'm trying to fill, with ART_COUNT from the GS point feature class.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 16:24:15 GMT

the resolution of that screenshot prevents anyone apart from the NSA reading it unfortunately.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 16:27:55 GMT

Ha, hopefully this is better?

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 16:34:21 GMT

no, forget about ART_COUNT, just use TOT_GS with a SUM merge rule, otherwise a field map is created of the sum of ART_COUNT instead of TOT_GS (which is NULL + NULL + ...).

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 16:45:39 GMT

But I do want to Sum ART_COUNT from the GS table and put the Sum in the TOT_GS field. TOT_GS is just 0s right which needs the sum of ART_COUNT of all intersecting GS points. Does that make sense?

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 17:05:44 GMT

OK to save this getting muddled just do this:

add a new field using the + icon -> name the field whatever you want. on the right hand side Add Source and set that to ART_COUNT and click 'add selected' set the merge rule to SUM. keep all the other fields as original default.

then run

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 17:15:46 GMT

Did that, as attached screen shot, added field GSTEST, which came out as NULL...

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

DavidPike — Tue, 11 May 2021 17:33:46 GMT

you may accidentally have a selection on a layer?

Should be One to one not one to Many? that seems like the issue.

If doesn't work, just try with all the defaults, and don't add a new field or change anything except for changing the merge rule.

Re: Model Builder: Calculating Attribute in Polygon Based on Point Values within

KJVersar — Tue, 11 May 2021 17:45:13 GMT

Ahhh, I think it was the one to many that was the issue. Thought to use that since there are multiple GS points within a cell but it looks like I don't need it. Thanks for your help!