export_DX.py

# BEFORE YOU RUN THIS SCRIPT:
#
# 1-Start with a feature dataset that contains: a polyline feature class 
#   of tracks, a point feature class of switches, and a trace network.
#
# 2-Select all features, then built a Basic Diagram.
#
# 3-Run the Apply Relative Mainline network diagram layout tool.
#
# 4-On that diagram, run the Export Diagram Content tool to export the
#   diagram to a JSON file.
#
# 5-Go back to the original tracks and switches layers, and export them
#   both to be two new feature classes. Basically carbon copies of these
#   two original feature classes.
#
# 6-In the code below:
#   a. update the path to the gdb folder in which you stored the fc copies
#      you created in Step 5
#   b. update the feature class names in the two .UpdateCursor lines below
#      to be the feature class names of the copies you created in Step 5.
#   c. update the path and file name of the json file that you exported
#      in Step 4.
#
# 7-Run the script below. Each record of the two copied feature classes
#   will be edited so that the features in the Shape field are updated
#   from the original geographic feature to the new schematic feature

import arcpy
import json


# location of FGDB folder the contains the edges and junctions feature classes
arcpy.env.workspace = r'C:\path\to\your\file.gdb'

# edges/junctions feature classes, and the oid and shape fields
cursorPolylines = arcpy.da.UpdateCursor("your_tracks_fc_name", ["OBJECTID", "SHAPE@"])
cursorPoints = arcpy.da.UpdateCursor("your_switches_fc_name", ["OBJECTID", "SHAPE@"])
    

# open the json file that contains the exported diagram
jsonDX = open(r'C:\path\where\you\stored\the\diagram_export.json', 'r')

# load the json object contents into a python object tree structure
dataDX = json.load(jsonDX)

# get the spatial reference wkid
wkid = dataDX['spatialRef']['wkid']


# EXPORT JUNCTIONS FROM DIAGRAM TO FGDB POINT FEATURE CLASS

# for every "junction" feature in the exported diagram json file, 
# create a point feature geometry, and write it into the shape field  
# of the associated record in the "switches" point feature class.
#
# ...important ... 
# the order of the features in the exported diagram json file is NOT 
# the same order as the records in the feature class you're editing, 
# so, for each record in the feature class, get its oid, then loop 
# thru the json until you find the object with the same oid.
#
# once you found the correct object in the json, construct a point
# geometry object and write it into the "switches" point feature class' 
# shape field.

for row in cursorPoints:
    oidFC = row[0]
    for junction in dataDX['junctions']:
        oidDX = junction['attributes']['OBJECTID']
        if oidDX == oidFC:
            x = junction['geometry']['x']
            y = junction['geometry']['y']
            z = junction['geometry']['z']
            m = junction['geometry']['m']
            pt = arcpy.Point(x,y,z,m)
            ptGeometry = arcpy.PointGeometry(pt, wkid)
            row[1] = ptGeometry
            cursorPoints.updateRow(row)
            break
    

# EXPORT EDGES FROM DIAGRAM TO FGDB POLYLINE FEATURE CLASS

# for every "edge" feature in the exported diagram json file, create 
# a polyline feature geometry, and write it into the shape field of the 
# associated record in the "tracks" polyline feature class.
#
# ...important ... 
# the order of the features in the exported diagram json file is NOT the 
# same order as the records in the feature class you're editing, so,
# for each record in the feature class, get its oid, then loop thru
# the json until you find the object with the same oid.
#
# once you found the correct object in the json, construct a polyline
# object and write it into the "tracks" polyline feature class' shape field.
#
# also, for some reason, the x,y,z,m values for each vertex in the
# json file are named 0,1,2,3

for row in cursorPolylines:
    oidFC = row[0]
    for edge in dataDX['edges']:
        oidDX = edge['attributes']['OBJECTID']
        if oidDX == oidFC:            
            pathNew = arcpy.Array()
            pathJson = edge['geometry']['paths'][0]
            z = 0
            hasZ = edge['geometry']['hasZ']
            m = 0
            hasM = edge['geometry']['hasM']
            for vertex in pathJson:
                x = vertex[0]
                y = vertex[1]
                if hasZ: z = vertex[2]
                if hasM: m = vertex[3]
                pt = arcpy.Point(x,y,z,m)
                pathNew.add(pt)
            paths = arcpy.Array()
            paths.add(pathNew)
            pline = arcpy.Polyline(paths, wkid)
            row[1] = pline
            cursorPolylines.updateRow(row)
            break


# clean up cursors and report complete
del cursorPolylines
del cursorPoints
print("DONE!!")