Sorts a polygon feature class by descending X and ascending Y, to obtain the spatial order of the polys from left to right, top to bottom. Bypasses the Advanced licence needed to do this in the Sort tool.

sortFeatureClassByExtent.py

#
# @date 13/07/2015
# @author Cindy Williams
#
# Sorts a polygon feature class by descending X and ascending Y,
# to obtain the spatial order of the polys from left to right,
# top to bottom. Bypasses the Advanced licence needed to 
# do this in the Sort tool.
#
# For use in the Python window in ArcMap.
#

import arcpy

mxd = arcpy.mapping.MapDocument("CURRENT")
lyr = arcpy.mapping.ListLayers(mxd, "DDP")[0]

# Get the extent of each feature, and store as tuple (name, x coord of top right, y coord of top right)
ddp = [(row[0], row[1].extent.XMax, row[1].extent.YMax) for row in arcpy.da.SearchCursor(lyr, ("Name", "SHAPE@"))]

# Sort by x descending
ddp.sort(key=lambda row:row[1], reverse=True)

# Sort by y ascending
ddp.sort(key=lambda row:row[2])

# Reverse the list to get the L->R, T->B order
dct = {}
# Must still be optimised
for i, j in enumerate(reversed(ddp)):
    # Key is name, value is index + 1
	dct[j[0]] = i + 1
	
# Write values back to feature class
with arcpy.da.UpdateCursor(lyr, ("Name", "MapNum")) as cursor:
	for row in cursor:
		row[1] = dct[row[0]]
		cursor.updateRow(row)