Find a polygon for a single point in Python script

[MarcWouters]

Hi all,

I am writing a Python script in which I build a geodatabase, based on several inputs.

At one point, I am looping over a number of points (X,Y) which need to be treated individually using several criteria. 
One criterium is the polygon in which this point is located. This polygon comes from a feature table with a number of other fields.

There are several tools (Intersect, SelectByLocation, SpatialJoin, ....) which might help doing this, but they all are based on input and output tables.

How can I extract this one polygon, and linked fields, from that table, without having to make temporary input and output tables ?

In an ideal world, it could look like this :

for i in range (0, numberOfPoints):

      inputPoint = arcpy.Point(X, Y)

      findFeature(tableWithPolygons, inputPoint, outputFeature)

      myValue = outputFeature.value

      # based on this value, I can do further processing

Thanks for pointing me in the right direction

[JoshuaBixby]

Does some part of this involve the ArcGIS API for Python or are you just using ArcPy, or aren't you sure?  I am sharing with Python‌ since this seems to be ArcPy related.

[MarcWouters]

I don't clearly understand the difference between ArcPy and ArcGIS API for Python.

Aren't they both using Python functions to get things automated which you can do manually in ArcGIS Pro ?

[JoshuaBixby]

See https://community.esri.com/thread/187844-arcpy-api-vs-arcgis-python-api-eventual-deprecation-of-arcp... 

[JoshuaBixby]

With the information provided, I can only provide a rough workflow that may or may not meet your needs:

SR = arcpy.Describe(tableWithPolygons).spatialReference
layerPolygon = arcpy.MakeFeatureLayer_management(tableWithPolygons, "layerPolygon")

for i in range(0, numberofPoints):
    inputPointGeometry = arcpy.PointGeometry(arcpy.Point(X,Y), SR)
    arcpy.SelectLayerByLocation_management(
        layerPolygon,
        "INTERSECT",
        inputPointGeometry,
        "",
        "NEW_SELECTION"
    )
    with arcpy.da.SearchCursor(layerPolygon, "*") as cur:
        for row in cur:
            myValue = # retrieve value(s) 
            # based on this value, I can do further processing‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

A few comments:

• Tools like Intersect, Select By Location, Spatial Join work on geometries, so you will have to create a Point Geometry from your Point.
  • To create a Point Geometry, you will have to (or really should) have a spatial reference.  My code above assumes the Point Geometry has the same spatial reference as the polygon layer.
• If you are going to be repeatedly executing spatial queries against a feature class, it is best to make a feature layer outside of the loop.
• The code above assumes there may be more than one record returned from the spatial query.  If only one record is returned, at most, the code can be changed up a bit.

[MarcWouters]

Hello Joshua,

Sorry for the late reply (I'm leaving my current position, and have lots of things to wrap up).

Thanks for the code snippet. 

I've implemented your proposal (with a few modifications), and it works OK. 
Unfortunately I cannot avoid temporary layers.

It's quite time consuming (a query for every single point), but I cannot do it with the complete table, because the Intersect tool doesn't keep my features in the same order, and this is something I MUST have.

Thanks again.

[JoshuaBixby]

If the polygon data set is already loaded into ArcMap as a layer, you don't need to create another layer, you can just use the already created one.  If the script is run outside of ArcMap, creating a feature layer in memory for processing isn't really an issue because the layer will go away when the script finishes.