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I have a set of points on a map, each with a unique location id, with one or more points within a number of polygons with unique polygon ids. I am trying to associate each location id with the number of shared points in its respective polygon.

To do so I used the intersect tool on the points feature and polygon feature, intersecting by polygon id. I then used the dissolve tool with the polygon id as the dissolve field and the location id COUNT in the statistics field. Then unchecked "create multipart features".

This leaves me with a table of points with the polygon id each point is in, and the number of points in each polygon. But removes the location id associated with each point. How can I keep the location id associated with each point?

Here is my table before being dissolved: enter image description here

Here is my dissolved table, I want to simply keep the location id for each point, but getting the count removes that field. Here is my dissolved table, before dissolving I had rows containing location ids for each point

I did something similar using spatial joins but need to see the differences in output using the intersect and dissolve tools.

closed as unclear what you're asking by BERA, Jochen Schwarze, whyzar, nmtoken, LaughU May 6 at 8:45

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  • What output do you want? The polygon fc with one field holding all intersecting Point ids? – BERA Apr 24 at 5:38
  • @BERA Im looking a fc with 3 fields: location id | polygon id (which polygon the point is in) | count of points in this polygon – Silverfin Apr 24 at 5:44
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Use Spatial Join instead of intersect-dissolve:

  1. Spatial Join with polygon as target features, Points as join features. Join operation JOIN_ONE_TO_ONE. You will get polygons with a join Count field of the number of Points.
  2. Spatial Join with Points as target feature as polygons as join features. You will get a Point fc with polygon attributes joined.
  3. Join first spatial join to the second one using field TARGET_FID as join field.
  • Thanks, I believe I have done just that and it seemed to work but as I said am looking to investigate differences between the spatial join and intersect/dissolve methods. – Silverfin Apr 24 at 6:07
  • This forum is for focused questions and answers, not for investigating differences, which is very unclear. – BERA Apr 24 at 6:15
  • I understand, im not trying to ask about what differences may occur but merely understand how to work with the dissolved tool and joins. Would joining by FID from my dissolved table back to my intersected table map the points to their ids correctly? Or is a new FID field created after the dissolve function. – Silverfin Apr 24 at 6:20
  • If you intersect Point and polygons, dissolve by polygon id, as far as i know you will loose Point ids. So dont use dissolve. You might be able to use Near tool, or Generate Near table. But why when spatial join does exactly what you want? – BERA Apr 24 at 6:24
  • I don't think doing the final join by TARGET_FID is accurate as I end with rows with 2 different PIN fields. For step 2 I have been spatial joining back onto the first spatial join fc but end up with some inaccurate join counts. – Silverfin May 2 at 21:25

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