topic Re: Python: select by Location and assign value from the source to the target in Python Questions

Python: select by Location and assign value from the source to the target

RyanFadd — Fri, 07 Mar 2014 01:10:13 GMT

Hi All

I have a polygon layer with a 'lot' field and a points layer. I would like to use python to select the points by location (to find what points are contained in what polygons) and assign the value in the 'lot' field from the polygon layer to the point that is contained in the relevant polygon feature. Not sure how to create that link between the 2 layers...

Any help is much appreciated.
Thank you

Re: Python: select by Location and assign value from the source to the target

GregSnelling — Fri, 07 Mar 2014 01:57:23 GMT

There are 3 ways I can think of:

1) Use arcpy to spatially join the lot attribute from the polygon to the point.
http://resources.arcgis.com/en/help/main/10.1/index.html#//00080000000q000000

2) Use ArcPy to convert polygons to points and keep the attributes. The points will be populated with the Lot values.
http://http://resources.arcgis.com/en/help/main/10.1/index.html#/Feature_To_Point/00170000003m000000/

3) Use ArcPy to Select By Location, then calculate the point field values to equal lot number from the selected polygon feature; then use iterations of this process for each polygon in your feature class.

In my opinion I'd go with option 2 because it's the easiest. Option 3 is probably a more of a "learning experience".

Have fun!

G

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Thu, 01 Sep 2016 21:00:31 GMT

Ryan,

Did you ever find a solution to your question? Which option did you choose?

Re: Python: select by Location and assign value from the source to the target

DarrenWiens2 — Thu, 01 Sep 2016 21:06:52 GMT

What's wrong with Spatial Join?

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Thu, 01 Sep 2016 21:17:22 GMT

Darren,

In my workflow option 3 might be a better an option. Spatial Join produces a whole new feature class as an output, instead of transferring an attribute from a selected polygon to the point features within the selected polygon. Thoughts?

Re: Python: select by Location and assign value from the source to the target

DarrenWiens2 — Thu, 01 Sep 2016 21:22:23 GMT

Oh I see. It probably depends somewhat on the size of the datasets. Suppose there are 1000 points. You could do 1000 individual selections/field calculations, or 1 spatial join (to an in-memory feature class if you don't want to keep it) then 1 join then 1 field calculation. I'm guessing the second option is faster, but haven't tested.

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Sat, 11 Dec 2021 21:28:00 GMT

Darren,

I know I am not an efficient python scripter, so bear with me. I have attempted to script it with spatial join. The goal is to calculate the zone of a concern for only the ones that the zone field is null. Both feature classes are in an enterprise environment (the concerns and the zones). Here is what I have so far from testing on a file geodatabase. I am not sure it is joining properly and the field calculator dies. Any suggestions?

# import modules
import arcpy

# Set workspaces
workspace = r'C:\ESRITest\GeoReportingSystem\Testing9116\Testing9116.gdb'
outWorkspace = r'C:\ESRITest\GeoReportingSystem\Testing9116\Scratch.gdb'

targetFeatures = r'C:\ESRITest\GeoReportingSystem\Testing9116\Testing9116.gdb\GeoReporting'
joinFeatures = r'C:\ESRITest\GeoReportingSystem\Testing9116\Testing9116.gdb\GRSAldermanic'

outfc = r'C:\ESRITest\GeoReportingSystem\Testing9116\Scratch.gdb\AldermanicSJ'

fieldmappings = arcpy.FieldMappings()
fieldmappings.addTable(targetFeatures)
fieldmappings.addTable(joinFeatures)

# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "GeoReporting Features", "GRSAldermanic"
arcpy.SpatialJoin_analysis(target_features=targetFeatures, join_features=joinFeatures, out_feature_class=outfc, join_operation="JOIN_ONE_TO_ONE", join_type="KEEP_COMMON", field_mapping=fieldmappings, match_option="INTERSECT", search_radius="", distance_field_name="")

print "Done with Spatial Join"

# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "AldermanicSJ"
arcpy.DeleteField_management(in_table=outfc, drop_field="SpecificConcern;DescriptionOfConcern;ReportingEmail;DateClosed;ConcernStatus;PriorityLevel;PrimaryDepartment;PrimaryContact;PrimaryInformation;DeptLogging;ReportingMethod;FollowUpRequest;FollowUpContactInfo;AldermanicDistrict;ApproriateYN;NUMVOTES;DaysToClose;Match_Addr;Loc_Name;created_user;created_date;last_edited_user;last_edited_date;Address;Visibility;Report_ID;DISTRICTID")

print "Done with Deleting Fields"

arcpy.MakeFeatureLayer_management(outfc, "outfc_view")
arcpy.MakeFeatureLayer_management(targetFeatures, "GRE_view")
# arcpy.MakeFeatureLayer_management(targetFeatures, "GRE_view")
arcpy.AddJoin_management("GRE_view", "ConcernID", "outfc_view", "ConcernID")

print "Joined Up Sir"

fieldName1 = "GRE_view.AldermanicDistrict"
fieldName2 = "!outfc_view.NAME!"

# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "GeoReporting Features"
arcpy.CalculateField_management(in_table=targetFeatures, field=fieldName1, expression=fieldName2, expression_type="PYTHON", code_block="")

print "Field Calculation Done"

arcpy.RemoveJoin_management(in_layer_or_view=targetFeatures)

print "Removed Join"

arcpy.DeleteFeatures_management(outfc)

print "Spatial Join feature class deleted"‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Python: select by Location and assign value from the source to the target

DarrenWiens2 — Fri, 02 Sep 2016 17:58:32 GMT

Perhaps try expression_type="PYTHON_9.3". If that doesn't work, can you provide the error message?

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Fri, 02 Sep 2016 18:04:49 GMT

ExecuteError: Failed to execute. Parameters are not valid.

Error 000728: Field GRE_view.AldermanicDistrict does not exist within table

Failed to to execute (CalculateField).

Re: Python: select by Location and assign value from the source to the target

DarrenWiens2 — Fri, 02 Sep 2016 18:22:06 GMT

Have you tried running through the workflow manually to see exactly what's going on? You could also verify the field names like:

print [i.name for i in arcpy.ListFields('GRE_view')‍‍]‍

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Sat, 11 Dec 2021 21:28:03 GMT

I am not quite sure what you mean by manual approach, but I have tried running things individually via arcmap, and each step of the script by itself. The only thing that does not "work" is the field calculate. I get a 000539 error Invalid field. Below is updated code. Thoughts?

# import modules
import arcpy

# Set workspaces
workspace = r'C:\ESRITest\GeoReportingSystem\Testing9116\Testing9116.gdb'
outWorkspace = r'C:\ESRITest\GeoReportingSystem\Testing9116\Scratch.gdb'

targetFeatures = r'C:\ESRITest\GeoReportingSystem\Testing9116\Testing9116.gdb\GeoReporting'
joinFeatures = r'C:\ESRITest\GeoReportingSystem\Testing9116\Testing9116.gdb\GRSAldermanic'

outfc = r'C:\ESRITest\GeoReportingSystem\Testing9116\Scratch.gdb\AldermanicSJ'

fieldmappings = arcpy.FieldMappings()
fieldmappings.addTable(targetFeatures)
fieldmappings.addTable(joinFeatures)

# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "GeoReporting Features", "GRSAldermanic"
arcpy.SpatialJoin_analysis(target_features=targetFeatures, join_features=joinFeatures, out_feature_class=outfc, join_operation="JOIN_ONE_TO_ONE", join_type="KEEP_COMMON", field_mapping=fieldmappings, match_option="INTERSECT", search_radius="", distance_field_name="")

print "Done with Spatial Join"

# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "AldermanicSJ"
arcpy.DeleteField_management(in_table=outfc, drop_field="SpecificConcern;DescriptionOfConcern;ReportingEmail;DateClosed;ConcernStatus;PriorityLevel;PrimaryDepartment;PrimaryContact;PrimaryInformation;DeptLogging;ReportingMethod;FollowUpRequest;FollowUpContactInfo;AldermanicDistrict;ApproriateYN;NUMVOTES;DaysToClose;Match_Addr;Loc_Name;created_user;created_date;last_edited_user;last_edited_date;Address;Visibility;Report_ID;DISTRICTID")

print "Done with Deleting Fields"

layerName1 = "outfc_view"
layerName2 = "GRE_view"

#calcExpression ="!AldermanicSJ.NAME!"


arcpy.MakeFeatureLayer_management(outfc, "outfc_view")
arcpy.MakeFeatureLayer_management(targetFeatures, "GRE_view")
# arcpy.MakeFeatureLayer_management(targetFeatures, "GRE_view")
arcpy.AddJoin_management("GRE_view", "ConcernID", "outfc_view", "ConcernID")

print [i.name for i in arcpy.ListFields('GRE_view')]

print "Joined Up Sir"

fieldName1 = "AldermanicDistrict"
fieldName2 = 'AldermanicSJ.NAME'
calcExpression ="!"+fieldName2+"!"


# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "GeoReporting Features"
arcpy.CalculateField_management(targetFeatures, fieldName1, calcExpression, "PYTHON")

#print "Field Calculation Done"

arcpy.RemoveJoin_management(layerName2,"AldermanicSJ")

print "Removed Join"

arcpy.Delete_management(r'C:\ESRITest\GeoReportingSystem\Testing9116\Scratch.gdb\AldermanicSJ')

print "Spatial Join feature class deleted"‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Fri, 02 Sep 2016 20:04:40 GMT

I should also add that when I did the line:

print [i.name for i in arcpy.ListFields('GRE_view')]

It showed me:

[u'GeoReporting.OBJECTID', u'GeoReporting.ConcernID', u'GeoReporting.GeneralConcern', u'GeoReporting.SpecificConcern', u'GeoReporting.DescriptionOfConcern', u'GeoReporting.ReportingEmail', u'GeoReporting.DateClosed', u'GeoReporting.ConcernStatus', u'GeoReporting.PriorityLevel', u'GeoReporting.PrimaryDepartment', u'GeoReporting.PrimaryContact', u'GeoReporting.PrimaryInformation', u'GeoReporting.DeptLogging', u'GeoReporting.ReportingMethod', u'GeoReporting.FollowUpRequest', u'GeoReporting.FollowUpContactInfo', u'GeoReporting.AldermanicDistrict', u'GeoReporting.ApproriateYN', u'GeoReporting.NUMVOTES', u'GeoReporting.DaysToClose', u'GeoReporting.GlobalID', u'GeoReporting.Match_Addr', u'GeoReporting.Loc_Name', u'GeoReporting.SHAPE', u'GeoReporting.created_user', u'GeoReporting.created_date', u'GeoReporting.last_edited_user', u'GeoReporting.last_edited_date', u'GeoReporting.Address', u'GeoReporting.Visibility', u'GeoReporting.Report_ID', u'AldermanicSJ.OBJECTID', u'AldermanicSJ.Join_Count', u'AldermanicSJ.TARGET_FID', u'AldermanicSJ.ConcernID', u'AldermanicSJ.GeneralConcern', u'AldermanicSJ.NAME']

I have tried various combinations of u'AldermanicSJ.NAME', but get that 000539 error

Re: Python: select by Location and assign value from the source to the target

DarrenWiens2 — Sat, 11 Dec 2021 21:28:06 GMT

This would be my guess:

fieldName1 = "GeoReporting.AldermanicDistrict"
fieldName2 = 'AldermanicSJ.NAME'
calcExpression ="!"+fieldName2+"!"


# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "GeoReporting Features"
arcpy.CalculateField_management(targetFeatures, fieldName1, calcExpression, "PYTHON")

Re: Python: select by Location and assign value from the source to the target

DavidBuehler — Sat, 11 Dec 2021 21:28:08 GMT

I got it to work. I had tried your recommendation with no success. After some trial and error and research, I figured it out. I had to use the view instead of the feature class to calculate on, and change the field variables to the use the output of the join. See below:

layerName1 = "outfc_view"
layerName2 = "GRE_view"

#calcExpression ="!AldermanicSJ.NAME!"


arcpy.MakeFeatureLayer_management(outfc, "outfc_view")
arcpy.MakeFeatureLayer_management(targetFeatures, "GRE_view")
# arcpy.MakeFeatureLayer_management(targetFeatures, "GRE_view")
arcpy.AddJoin_management("GRE_view", "ConcernID", "outfc_view", "ConcernID")

print [i.name for i in arcpy.ListFields('GRE_view')]

print "Joined Up Sir"

fieldName1 = u'GeoReporting.AldermanicDistrict'
fieldName2 = u'AldermanicSJ.NAME'
calcExpression ="!"+ fieldName2 +"!"


# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: "GeoReporting Features"
arcpy.CalculateField_management(layerName2, fieldName1, calcExpression, "PYTHON_9.3")‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍