topic Re: Identify a polygon to the right or left of a line in Spatial Data Science Questions

Identify a polygon to the right or left of a line

MarkVolz — Thu, 20 Aug 2020 13:04:55 GMT

Hello,

I have a road line feature class and a city township unit polygon feature class. One of the requirements of the line feature class is that I need to correctly identify which polygon is on either side of the line. The closest solution I found thus far makes the assumption that the line is strait. However, it is very possible that the line could be curved as well.

There are a couple ways that I could perform this, but I don't know how to implement these solutions.

Perhaps there is already a geoprocessing tool, python script, or Aracade script that can already do this. This would be preferred.
If I could create a point halfway down the line that is offset to the right or left by several feet then I could use that point to identify the line and rejoin the needed point value back into the correct field in the line feature.

This should be very similar to the calculate adjacent fields, except it should identify values to the right or left of a line.

Thanks for any help!

Re: Identify a polygon to the right or left of a line

DuncanHornby — Fri, 21 Aug 2020 13:50:09 GMT

Suggest you look at this thread.

Re: Identify a polygon to the right or left of a line

datasolutions — Wed, 11 Jan 2023 19:53:22 GMT

Anyone find a solution/calculation for this? I located a rule attribute in the Address Data Management Solution, but it is not working.

Re: Identify a polygon to the right or left of a line

JoshSaad1 — Fri, 01 Mar 2024 14:33:02 GMT

I just figured this out the other day. You can use the Offset function in Arcade. Here's the code that I use to calculate the neighborhood on the left-side of a road segment.

//Set the neighborhood dataset, selecting only the neighborhood name field.
var fsNbrhd = FeatureSetByName($datastore, "GIS.DBO.Neighborhood", ["nbrhdname"])

//Specifies the left-side of the road. If the offset is greater than 0, it will be the right-side.
var RoadLeft = offset($feature, -1, 'feet', 'square')

//Selects the neighborhood polygon on the left-side of the road.
var fsNbrhdLeft = Intersects(fsNbrhd, RoadLeft)

//Returns only the first intersecting polygon, in case there are overlaps.
var NbrhdLeft = First(fsNbrhdLeft)

if(NbrhdLeft == null) return null

//Returns the name of the first intersecting neighborhood polygon on the left-side of the road segment.
return NbrhdLeft.nbrhdname

Re: Identify a polygon to the right or left of a line

ChelseaRozek — Wed, 13 Mar 2024 21:17:00 GMT

Thanks for posting that! That's a clever way of doing it. This is going to be so helpful.