Grid segmentation for density

GrahamDriver · ‎08-23-2023

Hi all,

I'm fairly new to ArcGIS PRO and would appreciate some help walking me through this. Please see the images below for reference.

I have a map with a grid system on it and a density map of data points. I want to create a value for each grid showing how dense the features are in each grid, e.g., ., 0=nothing > 20=extremely dense. Something which I can then colour appropriately in symbology.

How do I go about doing this? Seems like it should be fairly simple but I do not know the procedures. Any help you can give me would be amazing, thank you.

clt_cabq · ‎08-23-2023

There are probably a ton of approaches to this depending on what you really want. I'm presuming that grid is actually a polygon feature class here. I'm also assuming by density you mean a frequency count of points within each grid square. The simplest approach would be:

do a spatial join between the polygons (your target features) and the points (join features), setting your join operation to 1:m, and match option to intersect.
With the result of that operation, use the summarize function against the unique grid square ID the resulting table will give you the count of every time you have a given grid cell in your spatial join result and that is the number you want - my recollection is this is in a field named 'frequency'.
Join that table back to the original grid cells using the unique grid cell ID value, create a new integer field named something like "point frequency" and then calculate that using the field calculator to equal the frequency field from the joined table. Unjoin your table. Then you can symbolize against that newly populated frequency field however you like.

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clt_cabq · ‎08-23-2023

There are probably a ton of approaches to this depending on what you really want. I'm presuming that grid is actually a polygon feature class here. I'm also assuming by density you mean a frequency count of points within each grid square. The simplest approach would be:

do a spatial join between the polygons (your target features) and the points (join features), setting your join operation to 1:m, and match option to intersect.
With the result of that operation, use the summarize function against the unique grid square ID the resulting table will give you the count of every time you have a given grid cell in your spatial join result and that is the number you want - my recollection is this is in a field named 'frequency'.
Join that table back to the original grid cells using the unique grid cell ID value, create a new integer field named something like "point frequency" and then calculate that using the field calculator to equal the frequency field from the joined table. Unjoin your table. Then you can symbolize against that newly populated frequency field however you like.

GrahamDriver · ‎08-23-2023

That's great! I managed to get it done by using the 'Summarize Within' tool on the grid (input which created a 'Count of Points' section in the data table, which I could then manipulate with graduated colours symbology. But your direction to the relevant toolset helped enormously! thank you

clt_cabq · ‎08-23-2023

That's great, glad it helped. There are always multiple ways to do stuff, figuring where to start can sometimes be challenging.