topic Re: Update layer based on another layer in Python Questions

Update layer based on another layer

2Quiker — Tue, 11 Jul 2023 20:17:46 GMT

I need to update the PrivateRoads 'Owner' field based on what city the private road is in. I have the following but it take for ever but doesn't populate the correct city. I know I can do a spatial join but I don't want to create a separate layer.

import sys, os, arcpy import arcpy ## Works in file geodatabase arcpy.env.overwriteOutput = True workspace = "C:/temp/temp.gdb" PR = "PrivateRoads" CityLimits = 'City_Limits' arcpy.MakeFeatureLayer_management(PR, "polyLyr") arcpy.MakeFeatureLayer_management(CityLimits, "CitLyr") with arcpy.da.UpdateCursor(PR, ['SHAPE@', 'OID@', 'Owner']) as cursor: for row in cursor: arcpy.management.SelectLayerByLocation("polyLyr", "HAVE_THEIR_CENTER_IN", "CitLyr", "", "NEW_SELECTION") with arcpy.da.SearchCursor("CitLyr", ['CITY']) as cCursor: for cRow in cCursor: row[2] = cRow[0] cursor.updateRow(row)

Re: Update layer based on another layer

DonMorrison1 — Tue, 11 Jul 2023 23:34:04 GMT

I would try to restructure the code roughly as follows:

import sys, os, arcpy import arcpy ## Works in file geodatabase arcpy.env.overwriteOutput = True workspace = "C:/temp/temp.gdb" PR = "PrivateRoads" CityLimits = 'City_Limits' arcpy.MakeFeatureLayer_management(PR, "polyLyr") arcpy.MakeFeatureLayer_management(CityLimits, "CitLyr") arcpy.management.SelectLayerByLocation("polyLyr", "HAVE_THEIR_CENTER_IN", "CitLyr", "", "NEW_SELECTION") pr_oid_to_city_name = dict() # Add code here to use a search cursor scan the polyLyr and # populate the dict that maps the pr oid to the city name with arcpy.da.UpdateCursor(PR, ['OID@', 'Owner']) as cursor: for oid, owner in cursor: if oid in pr_oid_to_city_name.keys(): cursor.updateRow([oid, pr_oid_to_city_name[oid])

Re: Update layer based on another layer

2Quiker — Wed, 12 Jul 2023 22:14:17 GMT

I tried the following but the print only prints one of the cities and for some reason it's populates only a a few private roads that are not inside city limits. Some of these will not be in a city.

I honestly thought it would simple and wouldn't' involve .keys or dicts.

import sys, os, arcpy arcpy.env.overwriteOutput = True workspace = "C:/temp/temp.gdb" PR = "PrivateRoads" CityLimits = 'City_Limits' arcpy.MakeFeatureLayer_management(PR, "polyLyr") arcpy.MakeFeatureLayer_management(CityLimits, "CitLyr") arcpy.management.SelectLayerByLocation("polyLyr", "HAVE_THEIR_CENTER_IN", "CitLyr", "", "NEW_SELECTION") pr_oid_to_city_name = dict() # Add code here to use a search cursor to scan the polyLyr and # populate the dict that maps the pr OID to the city name with arcpy.da.SearchCursor("CitLyr", ['OID@', 'CITY']) as search_cursor: for oid, city_name in search_cursor: pr_oid_to_city_name[oid] = city_name print(pr_oid_to_city_name[oid]) # Start an edit session. Must provide the workspace. edit = arcpy.da.Editor(workspace) # Edit session is started without an undo/redo stack for versioned data # (for the second argument, use False for unversioned data) edit.startEditing(True) # Start an edit operation edit.startOperation() fields = ['OID@', 'Owner'] with arcpy.da.UpdateCursor(PR, fields) as cursor: for row in cursor: oid = row[0] if oid in pr_oid_to_city_name: row[1] = pr_oid_to_city_name[oid] cursor.updateRow(row) edit.stopOperation() # Stop the edit session and save the changes edit.stopEditing(True)

Re: Update layer based on another layer

2Quiker — Thu, 13 Jul 2023 17:56:53 GMT

I was able to accomplish what I needed with the following.

PR = "PrivateRoads" CityLimits = 'City_Limits' arcpy.MakeFeatureLayer_management(PR, "polyLyr") arcpy.MakeFeatureLayer_management(CityLimits, "CitLyr") unique_strings = [] with arcpy.da.SearchCursor("CitLyr", 'CITY') as cursor: for row in cursor: unique_strings.append(row[0]) #print (unique_strings) for unique in unique_strings: arcpy.SelectLayerByAttribute_management("CitLyr", 'NEW_SELECTION', "CITY = '{}'".format(unique)) arcpy.SelectLayerByLocation_management("polyLyr", 'HAVE_THEIR_CENTER_IN', "CitLyr", "", "NEW_SELECTION") with arcpy.da.UpdateCursor(PR, 'Owner') as cursor: for row in cursor: row[0] = unique cursor.updateRow(row)