Arcpy Network analyst - Perform OD Matrix Cost in loop

Question

I want to perform OD Matrix Cost in loop for each locations group inside a feature class.

As output, I want a lines feature class per group.

import arcpy

arcpy.env.overwriteOutput = True

def execute():
    network_dataset = arcpy.GetParameter(0)
    impedenace_attribute = arcpy.GetParameter(1)
    locations_fc = arcpy.GetParameter(2)
    sort_field = arcpy.GetParameter(3)
    group_by_field = arcpy.GetParameter(4)
    output_workspace = arcpy.GetParameter(5)
    arcpy.env.workspace = output_workspace
    calculate_OD(network_dataset, impedenace_attribute, locations_fc, group_by_field, sort_field, output_workspace)

def calculate_OD(network_dataset, impedenace_attribute, locations_fc, group_by_field, sort_field, output_workspace):
    group_by_list = sorted(set((row[0] for row in arcpy.da.SearchCursor(locations_fc, group_by_field))))

    OD_Layer = arcpy.MakeODCostMatrixLayer_na(network_dataset, "OD_Matrix_Layer", impedenace_attribute)
    OD_Layer = OD_Layer.getOutput(0)

    for group in group_by_list:
        expression = u"{} = '{}'".format(group_by_field, group)
        group_layer = arcpy.MakeFeatureLayer_management(locations_fc, "locations_{}".format(group), where_clause=expression)
        group_fc = arcpy.CopyFeatures_management(group_layer, "OD_locations_{}".format(group))

        subLayerNames = arcpy.na.GetNAClassNames(OD_Layer)

        originsLayerName = subLayerNames["Origins"]
        arcpy.na.AddLocations(OD_Layer, originsLayerName, group_fc, sort_field=sort_field, append="CLEAR")

        destinationLayerName = subLayerNames["Destinations"]
        arcpy.na.AddLocations(OD_Layer, destinationLayerName, group_fc, sort_field=sort_field, append="CLEAR")

        arcpy.na.Solve(OD_Layer,"HALT")

        #save output in feature class (this generate the error below)
        arcpy.CopyFeatures_management(OD_Layer, "OD_output_{}".format(group))

execute()

However, I have a problem when copying the ODLines sublayer to a new feature class.

ExecuteError: Failed to execute. Parameters are not valid. ERROR 000840: The value is not a Feature Layer. ERROR 000840: The value is not a Raster Catalog Layer.

Answer 1

You can't copy the OD matrix layer to a lines feature class directly. This OD matrix layer is a group layer, you need to retrieve the lines layer within the group. Try this:

arcpy.na.Solve(OD_Layer, "HALT")
lines = arcpy.mapping.ListLayers(OD_Layer, subLayerNames["ODLines"])[0]
arcpy.CopyFeatures_management(lines, "OD_Layer_{}".format(group))