topic Re: Python script to find all layers intersecting a polygon in Python Questions

Python script to find all layers intersecting a polygon

JoseSanchez — Wed, 10 Mar 2021 20:40:07 GMT

Hello everyone,

I am looking for a Python script to find all layers intersecting a polygon.

Thanks

Re: Python script to find all layers intersecting a polygon

DavidPike — Wed, 10 Mar 2021 20:48:00 GMT

what do you mean by layer?

Re: Python script to find all layers intersecting a polygon

DanPatterson — Wed, 10 Mar 2021 21:19:12 GMT

Intersection is an intensive process. There is no simple check, the intersection has to be made and to complicate matters, you need to have an advanced license to perform more than a pairwise intersection.

Polygon—ArcGIS Pro | Documentation

in arcpy the polygon class has an intersects method which checks all shapes and performs the intersection.

there is also an "overlaps" property that does a similar thing, but returns a boolean but not the actual intersection (see clarification in that section of the help).

Loading all the layers, setting them selectable, then selecting your polygon in the map would quickly allow you to see whether there is any intersection and the geometry type of the selection.

I won't even address projection differences... a geometry may "intersect" another geometry after projection differences are taken into account.

Re: Python script to find all layers intersecting a polygon

JoseSanchez — Wed, 10 Mar 2021 21:27:24 GMT

From a specific polygon shape in a polygon feature class find all feature classes, points, lines, and polygons, that intersect with the polygon.

The goal is to find all the assets located in a project (polygon): devices (points), pipes (lines), other polygons (municipality, commission district, etc).

Thanks

Re: Python script to find all layers intersecting a polygon

JoshuaBixby — Wed, 10 Mar 2021 21:58:05 GMT

The Select Layer By Location tool allows for an ArcPy Geometry object to be passed as the selecting layer. I would extract the polygon you want, store it in an ArcPy Geometry, then loop through all your feature layers in the map using Select Layer By Location on each one (with mixed geometry types, I would use basic intersection). After running Select Layer By Location, you run Get Count to see how many features were selected.

Re: Python script to find all layers intersecting a polygon

JoeBorgione — Wed, 10 Mar 2021 22:20:32 GMT

I'm wondering what is meant by 'looking for'....

Re: Python script to find all layers intersecting a polygon

Anonymous User — Wed, 10 Mar 2021 23:32:25 GMT

I did this not too long ago and thought I'd share the code. Had to compare two featureclasses of polygons for intersecting features so I looped through one to select the other/ count the other like @JoshuaBixby described.

def intersectLayers(): bldgFp = os.path.join(wrkingdb, r'bldg_footprints') bldgFP_Lyr = arcpy.MakeFeatureLayer_management(bldgFp, "bldgFP_lyr") with arcpy.da.SearchCursor(pictBldgFP, ['OBJECTID', 'SHAPE@']) as cur: for row in cur: curIntersect = arcpy.SelectLayerByLocation_management(bldgFP_Lyr, "INTERSECT", row[1], '', 'NEW_SELECTION') intersectCnt = int(arcpy.GetCount_management(curIntersect).getOutput(0)) if intersectCnt > 0: print(f'{row[0]} intersects with {intersectCnt} features')

Re: Python script to find all layers intersecting a polygon

JoseSanchez — Thu, 11 Mar 2021 14:06:56 GMT

JeffK thanks for sharing.

Re: Python script to find all layers intersecting a polygon

JohnMorgan — Mon, 20 Sep 2021 01:38:19 GMT

Nice work, Jeff!

Re: Python script to find all layers intersecting a polygon

JohnMorgan — Mon, 20 Sep 2021 12:41:54 GMT

I will just add that if you are working with a lot of features it may help to divide and conquer with a subsection first such as

intersect_lyr = arcpy.SelectLayerByLocation_management(one_fc, 'INTERSECT', two_fc)

Derek