Hi,
I put this together quickly using Pro but I'm pretty sure it should run from the Python window in ArcMap too:
fishnet = ""
fieldname = ""
fields = ["SHAPE@Y"].append(fieldname)
ys = [row[0] for row in arcpy.da.SearchCursor(fishnet, "SHAPE@Y")]
ysDict = {}
uniqueys = sorted(list(set(ys)))
for y in luniqueys:
if luniqueys.index(y) % 2 == 0:
ysDict[y] = 1
else:
ysDict[y] = 2
with arcpy.da.UpdateCursor(fish, ["SHAPE@Y", "val"]) as ucur:
for row in ucur:
row[1] = valueDict[row[0]]
ucur.updateRow(row)
Just enter in the name of the layer and the field name that stores the values (1 or 2) in there. Also make sure that field is an integer field. Basically this script finds all the features unique y values, lays them out in order and assigns them a 1 or 2 depending on if its index is odd or even, then adds that value back to the feature.