"Replicator Grid" Blender script

This Blender script creates a 2D grid of replicated objects with a descending line of parenting control, running left to right, then down to the next row. The following video demonstrates:

 
 

# ---------
# Tested in Blender 2.75a and 2.76
# Makes a 'replicator grid' -- multiple copies of a given object, parented in a tranformation-control chain.
# Provides a single empty that controls the relative size, displacement and rotation of each successive object in relation to
# its parent.
#
# Usage: 
# Change the number of rows and columns below.
# Select target object to be replicated.
# Run the script.
# If you did this with an object named 'cube', for example,
# You will end up with a 'cube_replicator' empty, below which all of the duplicated objects
# have been parented.
# And you will have a new cube_replicator_control empty, which can be moved, scaled and rotated
# to control the overall replicator grid.

# Bret Battey / BatHatMedia.com September 2015
# ---------
# 

import bpy
from bpy.props import *

# specify number of rows and columns here!
rows = 5
columns = 5

# The following function is adapted from Nick Keeline "Cloud Generator" 
# addNewObject in object_cloud_gen.py

def duplicateObject(scene, name, copyobj):

    # Create new mesh
    mesh = bpy.data.meshes.new(name)

    # Create a new object.
    ob_new = bpy.data.objects.new(name, mesh)
    tempme = copyobj.data
    ob_new.data = tempme.copy()
    ob_new.scale = copyobj.scale
    ob_new.location = copyobj.location

    # Link new object to the given scene and select it.
    scene.objects.link(ob_new)
    ob_new.select = True

    return ob_new            


# Build the parenting chain of replications tied to empties and control 
# constraints. If we built a parented chain of objects, we wouldn't be able to 
# transform each object independently. So instead we build a parented chain of
# empties, then parent each duplicated object to one of the empties.

def gridOfReps(rows, cols, source_obj, ctrl, scene):
    for row in range(rows):
        for col in range(cols):
            #Create a locator empty
            bpy.ops.object.add(type="EMPTY", location=(0,0,0))
            rep_loc = bpy.context.object
            # The first empty becomes the root of the whole beast, and the 
            # source object gets parented to it
            if((row == 0) and (col == 0)):
                rep_loc.name = source_obj.name+"_replicator"
                parent_obj = rep_loc
                prev_row_locator = rep_loc
                source_parent = source_obj.parent
                # If the source object has a parent, locate and parent 
                # the new replicator base empty to that.
                if((source_parent) and (source_parent.type == 'EMPTY')):
                    rep_loc.location = source_parent.location
                    rep_loc.parent = source_parent
                # Otherwise just position the base empty to the source obj,
                # zero the source obj location, and parent to the base
                else:  
                    rep_loc.location = source_obj.location
                    source_obj.location = (0,0,0)
                    source_obj.parent = rep_loc   
            else: 
                rep_loc.name = "rep_loc_r"+str(row)+"c_"+str(col)  # name can't 
                    #be specified via the .add method
                rep_loc.parent = parent_obj # parent to the previous locator
                # First locator in each row other than 0 gets special treatment
                if((row > 0) and (col == 0)):
                    # First location constraint locks to the prev. row locator
                    constraint = rep_loc.constraints.new("COPY_LOCATION")  
                    constraint.target = prev_row_locator
                    constraint.use_x = True
                    constraint.use_y = True
                    constraint.use_z = True       
                    constraint.owner_space = "WORLD"
                    constraint.target_space = "WORLD"
                    constraint.influence = 1.0
                    # Second location constraint implements the z offset 
                    # from the controller      
                    constraint = rep_loc.constraints.new("COPY_LOCATION")  
                    constraint.target = ctrl
                    constraint.use_x = False 
                    constraint.use_y = False
                    constraint.use_z = True       
                    constraint.owner_space = "LOCAL"
                    constraint.target_space = "WORLD"
                    constraint.influence = 1.0
                    constraint.use_offset = True   # use the controller's 
                    # location as an offset rather than an absolute location
                    # And ready this locator to be basis of next row position
                    prev_row_locator = rep_loc
                else:
                    # For other items in a row, offset location x on basis of 
                    # controller
                    constraint = rep_loc.constraints.new("COPY_LOCATION")  
                    constraint.target = ctrl
                    constraint.use_x = True  # for offsetting a row, only x is 
                        # drawn from the controller 
                    constraint.use_y = False
                    constraint.use_z = False       
                    constraint.owner_space = "LOCAL"
                    constraint.target_space = "WORLD"
                    constraint.influence = 1.0
                    constraint.use_offset = True   # use the controller's 
                        #location as an offset rather than an absolute location
                # For all locators except the root, apply these influences from 
                    #the controller:
                # Copy_Rotation Constraint 
                constraint = rep_loc.constraints.new("COPY_ROTATION")  
                constraint.target = ctrl
                constraint.owner_space = "LOCAL"
                constraint.target_space = "WORLD"
                constraint.influence = 1.0
                # Copy_Scale Constraint. This will also cascade down the chain 
                    # due to the combined effect with the parenting 
                constraint = rep_loc.constraints.new("COPY_SCALE")  
                constraint.target = ctrl
                constraint.owner_space = "LOCAL"
                constraint.target_space = "WORLD"
                constraint.influence = 1.0
                # In all cases (except root), duplicate source object and parent
                    # to the replicator empty.
                # This strategy allows later transformations of the visible 
                    #object without influencing the children
                new_obj = duplicateObject(scene, "rep", source_obj)
                new_obj.parent = rep_loc    
                # Advance parent assignment
                parent_obj = rep_loc    
    return parent_obj

# get the source object

source_obj = bpy.context.object
source_loc = source_obj.location
source_scene = bpy.context.scene

# create and name the controller empty

bpy.ops.object.add(type="EMPTY", location=(0,0,0))
ctrl = bpy.context.object  
ctrl.name = source_obj.name+"_replicator_control"  # name can't be specified 
        #via the .add method

#replicate!
last_locator = gridOfReps(rows, columns, source_obj, ctrl, source_scene)