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How can I use field values to specify distance of NA Service Area Buffers?

Question asked by andrewfclark on May 6, 2019
Latest reply on Apr 15, 2020 by MMorang-esristaff

Hi,

 

I am using ArcGIS Pro 2.3.2 through Jupyter Notebook

 

I am trying to create a Service Area using Network Analysis (i.e., MakeServiceAreaAnalysisLayer_na) based on predefined distances identified in a field of the input table (i.e., field named 'cut_off'). I have created a field with the cutoff values in them formatted as '[2, 3, 4]'. Each feature in the point feature class has a different value in the cutoff value field. From the help files I can see that "This default cutoff value can be overridden on a per-facility basis by specifying individual break values in the facilities sublayer." Unfortunately I cannot find any example of how to do this. I have developed some code but it doesn't seem to override the default distances of "5, 10, 15" minutes. 

 

Here is the example code that doesn't seem to work:

 

#Import system modules
import arcpy
import os, datetime
import numpy as np
#Check out Network Analyst license if available. Fail if the Network Analyst license is not available.
if arcpy.CheckExtension("network") == "Available":
    arcpy.CheckOutExtension("network")
else:
    raise arcpy.ExecuteError("Network Analyst Extension license is not available.")

#Set environment settings
output_dir = r"C:\afclark82\ChildCare_Version2"
input_gdb = os.path.join(output_dir,"Default.gdb")
travel_mode = "[Meters, DriveTime]"
print("Environment settings set")

#The NA layers data will be saved to the workspace specified here
arcpy.env.workspace = input_gdb
arcpy.env.overwriteOutput = True

#Set local variables
network = os.path.join(input_gdb, "Network", "NetworkDataSet")
facilities = r"Locations\ChildCareLocations"
output_layer_file = os.path.join(output_dir, "SrvcAreasLyr.lyrx")

#verifying that the feature dataset "shortestpaths" is already in the geodatabase
if arcpy.Exists("ShortestPaths")==False:
    print(network)
   arcpy.CreateFeatureDataset_management(input_gdb, "ShortestPaths")

if len(arcpy.ListFields(facilities,"cutoffs"))==0:
    arcpy.AddField_management(facilities, "cutoffs", "TEXT")

arcpy.management.CalculateField(facilities, "cutoffs", '"[{}, {}, {}]".format(!Per50!,!Per62!,!Per75!)', "PYTHON3", None)
print("Create a new service area")

#Create a new service area layer.
result_object = arcpy.na.MakeServiceAreaAnalysisLayer(network,output_layer_file,travel_mode,"FROM_FACILITIES",cutoffs="breaks_minutes",polygon_detail="HIGH",geometry_at_overlaps="OVERLAP")

#Get the layer object from the result object. The service area layer can
#now be referenced using the layer object.
layer_object = result_object.getOutput(0)

#Get the names of all the sublayers within the service area layer.
sublayer_names = arcpy.na.GetNAClassNames(layer_object)
print("Store sublayers")

#Stores the layer names that we will use later
facilities_layer_name = sublayer_names["Facilities"]
polygons_layer_name = sublayer_names["SAPolygons"]

#The input data has a field for CentreID that we want to transfer to
#our analysis layer. Add the field, and then use field mapping to transfer
#the values.
arcpy.na.AddFieldToAnalysisLayer(layer_object, facilities_layer_name,"CentreID", "TEXT")
arcpy.na.AddFieldToAnalysisLayer(layer_object, facilities_layer_name,"cutoffs", "TEXT")
field_mappings = arcpy.na.NAClassFieldMappings(layer_object,facilities_layer_name)
field_mappings["CentreID"].mappedFieldName = "CentreID"
field_mappings["cutoffs"].mappedFieldName = "cutoffs"
print("field mapping")

#Load the day care centres as facilities.
arcpy.na.AddLocations(layer_object, facilities_layer_name, facilities,field_mappings, "")

# Add fields to the output Polygons sublayer for later use.
arcpy.na.AddFieldToAnalysisLayer(layer_object, polygons_layer_name,"CentreID", "TEXT")
arcpy.na.AddFieldToAnalysisLayer(layer_object, polygons_layer_name,"cutoffs", "TEXT")

#Get sublayers to work with later
facilities_sublayer = layer_object.listLayers(facilities_layer_name)[0]
polygons_sublayer = layer_object.listLayers(polygons_layer_name)[0]

#Get the Service Area Layers solver properties. This can be used to
#set individual properties later without re-creating the layer.
solver_properties = arcpy.na.GetSolverProperties(layer_object)

arcpy.na.Solve(result_object)
print ("added locations")

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