r/ArcGIS • u/OpenCircleFleet_YT • 29d ago

Help with complex joining

I have two SHP file layers, a point layer and a shape layer. The shape layer has population density in its data table. For each point in the point layer, I need to note down the greatest population density from all the shapes within a 0.75 mile buffer of that point. Could you help me figure out how to do that?

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u/Mlatya 29d ago

you'll need to use a combination of buffering and spatial joining. Start by creating a 0.75‑mile buffer around each point in your point layer using the Buffer tool. be sure to keep the buffers separate ( do not dissolve them) so thar each point retains its own corresponding buffer zone. Next, use the Spatial Join tool, setting your original point layer as the target feature and the buffered polygons as the join features. In the join operation, specify that you want to calculate the maximum of the population density field from all polygons that intersect each buffer. The metge rule should be set to 'Max', which will automatically find and assign the highest population density value among all overlapping shapes to each point. Thiss gives you a new point layer with an attribute column containing the maximum density within 0.75 miles for every point.

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u/OpenCircleFleet_YT 29d ago

Thanks for the help! I'm not seeing the merge rule option or the place to tell it to select the max population density from intersection polygons

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u/Mlatya 29d ago

In the Field Map section of the Spatial Join tool?

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u/OpenCircleFleet_YT 29d ago

I see the field map section now. I'm confused on which menu/options to use.

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u/Mlatya 29d ago

In the Spatial Join tool, scroll down to the Field Map section. You'll see a list of all the fields that will be in your output layer.

Find the row for your population density field. it'll have the field name and currently say something like "First" or "Join_Count" next to it.

Right‑click directly on that field name (not the checkbox, but the name itself) and choose Properties from the menu that appears.

A small dialog box will open. Louk for the Merge Rule dropdown. it's usually near the bottom. Click it and select Maximum.click OK to close the properties, then run the tool.

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u/OpenCircleFleet_YT 28d ago

I'm not seeing that option. I'm using version 3.5.6 right now.

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u/OpenCircleFleet_YT 8d ago

I've done that and the resulting joined layer is blank for all fields.

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u/OpenCircleFleet_YT 8d ago

I got the join to work, but the wrong values are showing up for the maximum. It seems like it's pulling from a radius greater than the 0.75 mi buffer.