Can I delete an empty layer using ezdxf?

Question

Is there no way to delete an empty layer from the layer list? I want to do the same thing as the autocad purge command.

I tried to write the code but it didn't work.

del_lay = [] 
for layer in dwg.layers:
    s = layer.dxf.name
    lay_= re.search(layer.dxf.name, s)
    if lay_:
      L = lay_.group()
      del_lay.append(L)
del_lay.remove("0") #0 layer cannot be deleted, so remove it from the list 

for Lay in del_lay:
    all_entities = dwg.modelspace().query('*[layer=="%s"]' % Lay)
    print(all_entities)
    for entity in all_entities: #If there is no entity in the layer
        if entity not in all_entities:
            delete_name = layer.dxf.name
my_lines = dwg.layers.get(delete_name)
dwg.layers.remove(my_lines)

When I check it myself, there is a layer where entity does not exist, but it is not executed.

NameError: name 'delete_name' is not defined

Answer 1

Firstly, consider that the following if statement will never be validated:

for entity in all_entities: #If there is no entity in the layer
    if entity not in all_entities:

Within the for loop you are iterating over the contents of all_entities, hence your test expression: entity not in all_entities will never return True since by the very definition of the for loop, entity must be a member of all_entities.

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In response to your main question: before removing a layer definition from a DXF file, you will need to ensure that the layer name has no references anywhere in the database.

This therefore necessitates iterating over all entities in the entire drawing database (i.e. primary entities in all drawing layouts, subentities (e.g. ATTRIB, VERTEX, SEQEND entities), entities within all block definitions, and also the block definition bookends (BLOCK, ENDBLK).