Selecting all Empties without Children - blender

Question

I have a large structured model with thousands of parts. During CAD export (to fbx), the file was simplified and many small parts (such as screws and washers) were removed. However, in Blender I now have many 'empties' without any children below it.
I'd like to select all the empties that have no children, so that I can delete them all.

Answer 1

Achim's script to select Empties without children can be optimized and simplified:
import bpy
# select empties
bpy.ops.object.select_by_type(extend=False, type='EMPTY')
empties = bpy.context.selected_objects
# remove elements with children from selection
for obj in empties:
if len(obj.children) > 0:
obj.select_set(False)
print('{} empties were selected'.format(len(bpy.context.selected_objects)))
To delete all Empties without children automatically you can modify this script like so
import bpy
iteration = 1
print('Iteration {}'.format(iteration))
iteration = iteration + 1
# select empties
bpy.ops.object.select_by_type(extend=False, type='EMPTY')
empties = bpy.context.selected_objects
print('Total empties: {}'.format(len(empties)))
while len(empties) > 0:
# deselect everyting
bpy.ops.object.select_all(action='DESELECT')
parents = []
# select childless nodes and collect its parents to check in next iteration
for obj in empties:
if len(obj.children) == 0:
obj.select_set(True)
if obj.parent is not None:
parents.append(obj.parent)
count = len(bpy.context.selected_objects)
if count == 0:
break
print('{} empties were selected'.format(count))
bpy.ops.object.delete(use_global=True, confirm=False)
empties = parents
print('Iteration {}'.format(iteration))
iteration = iteration + 1
print('Done')
The key trick here is that script checks deleted object parent if it became childless and iterates process untill no Empties without children left.

Answer 2

My python is a bit rusty and I'm certain, there are much better ways of doing this. However, here's a bpy script that does the trick.
Select the root empty and run the script. The selected empties can then be deleted.
To get all the empties in the entire tree, the script has to be run several times until no more empties are selected...
import bpy
root_object = bpy.context.object
empties = []
selected = []
def select_children_recursive(obj_parent):
for obj in obj_parent.children:
select_children_recursive(obj)
if obj.type == 'EMPTY':
empties.append(obj)
# call the function
select_children_recursive(root_object)
# deselect everyting
bpy.ops.object.select_all(action='DESELECT')
# select all empties that have NO children
for obj in empties:
if len(obj.children) == 0:
selected.append(obj)
obj.select_set(True)
print('{} empties were selected'.format(len(selected)))
print('Press x to delete them and re-run this script again multiple times in order to delete all empies throughout the entire structure.')