calculate_from_to.py

HelpDavid.py

import arcpy

streets = r'\\Mac\Downloads\streetsforlinearreferencing\streets_for_linear_referencing.shp'

fldFULLNAME = 'FULLNAME'


routes = {}
with arcpy.da.SearchCursor(streets, [fldFULLNAME, 'Shape@', 'OID@'], sql_clause=(None, 'ORDER BY {}'.format(fldFULLNAME))) as cursor:
    for name, shape, oid in cursor:
        routes.setdefault(name, []).append((oid, shape))

edits = {}

for route in routes:
    print(route)
    print(len(routes[route]))

    check_shapes = list(route)
    ordered_shapes = []
    ordered_start_point = None
    ordered_end_point = None
    max_tries = 20
    tries = 0

    while len(ordered_shapes) < len(routes[route]) and tries <= max_tries:
        print(len(ordered_shapes))
        for oid, shape in routes[route]:
            if len(ordered_shapes) == 0:
                ordered_shapes.append((oid, shape))
                ordered_start_point = shape.firstPoint
                ordered_end_point = shape.lastPoint
                continue

            if shape.firstPoint.equals(ordered_end_point):
                #: add to the end of the ordered_shapes
                ordered_shapes.append((oid, shape))
                ordered_end_point = shape.lastPoint
                continue

            if shape.lastPoint.equals(ordered_start_point):
                #: add to the beginning of ordered_shapes
                ordered_shapes.insert(0, (oid, shape))
                ordered_start_point = shape.firstPoint
                continue

        tries = tries + 1

    running_length = 0
    for oid, shape in ordered_shapes:
        miles = round(shape.length * 0.00062137, 3)
        edits[oid] = (running_length, miles)
        running_length = running_length + miles

print('making edits')
with arcpy.da.UpdateCursor(streets, ['OID@', 'F_DISTANCE', 'T_DISTANCE']) as ucursor:
    for oid, f, t in ucursor:
        if oid in edits:
            new_from, new_to = edits[oid]
            ucursor.updateRow((oid, new_from, new_to))

print('done')