How to add a prefix to layer names in AutoCAD using ezdxf

Question

I am trying to add a prefix to the layer names in a .dxf file. Here is my code:

import ezdxf

doc = ezdxf.readfile('infile.dxf')

layer_names = [layer.dxf.name for layer in doc.layers]
for old_name in layer_names:
    try:
        layer = doc.layers.get(old_name)
        new_name = 'MY_PREFIX_' + old_name
        layer.rename(new_name)
        print(f'Layer "{old_name}" renamed to "{new_name}".')
    except ValueError as exc:
        print(exc)

doc.saveas('outfile.dxf')

The layer list of infile.dxf looks like this:

When I run the snippet above I get this output:

Can not rename layer "0".
Layer "Layer1" renamed to "MY_PREFIX_Layer1".
Layer "Layer2" renamed to "MY_PREFIX_Layer2".
Layer "Layer3" renamed to "MY_PREFIX_Layer3".
Layer "Layer4" renamed to "MY_PREFIX_Layer4".
Can not rename layer "Defpoints".

Apparently the code works fine, but when I open outfile.dxf with AutoCAD, the list of layers includes two unwanted layers:

1. Defpoints (I can live with this).
2. Layer1, which is empty. Please note that Layer1 was the current layer when I saved infile.dxf from the AutoCAD application.

How can I avoid that these two layers show up in the list of layers of the Layer Property Manager?

Answer 1

The current layer is set to the old layer name "Layer1" and AutoCAD creates a new layer "Layer1", BricsCAD doesn't do that.

Rename the current layer to "0":

doc.header["$CLAYER"] = "0"

The "Defpoint" layer is protected and cannot be (easily) renamed or deleted.