C4D create unique material per face

[C4D]Unique material per face.py

import c4d
import random

#create a selection for each polygon
def create_poly_selection(obj):
    poly_count = obj.GetPolygonCount()
    tags = list()
    for i in xrange(poly_count):
        #create the tag and name it by poly_id
        tag = c4d.SelectionTag(c4d.Tpolygonselection)
        tag.SetName(str(i))
        
        #add tag to the scene
        doc.AddUndo(c4d.UNDOTYPE_NEW, tag)
        obj.InsertTag(tag)
        tags.append(tag)
        
    return tags

#assign 1 poly_id
def assign_selection(obj, tags_list):
    poly_count = obj.GetPolygonCount()
    if len(tags_list) != poly_count:
        return False
    
    for i, tag in enumerate(tags_list):
        bs = tag.GetBaseSelect()
        bs.Select(i)
        
    return True
    
#create materials for a given obj
def create_materials(number=6):
    mats = list()
    for i in xrange(number):
        mat = c4d.BaseMaterial(c4d.Mmaterial)
        mat.SetName(str(i))
        #assign random color
        mat[c4d.MATERIAL_COLOR_COLOR] = c4d.Vector(random.random(), random.random(), random.random())
        doc.AddUndo(c4d.UNDOTYPE_NEW, mat)
        doc.InsertMaterial(mat)
        mats.append(mat)
    
    return mats
    
#create texture tag where selection tag and material name are identical
def create_texture_tag(obj, tags):
    for tag in tags:
        name = tag.GetName()
        mat = doc.SearchMaterial(name)
        if not mat:
            continue
        
        texture_tag = c4d.BaseTag(c4d.Ttexture)
        texture_tag.SetName(name)
        texture_tag[c4d.TEXTURETAG_MATERIAL] = mat
        texture_tag[c4d.TEXTURETAG_RESTRICTION] = tag.GetName()
        texture_tag[c4d.TEXTURETAG_PROJECTION] = c4d.TEXTURETAG_PROJECTION_UVW
        doc.AddUndo(c4d.UNDOTYPE_NEW, texture_tag)
        obj.InsertTag(texture_tag)

def main():
    if not isinstance(op, c4d.PolygonObject):
        return
    
    doc.StartUndo()
    
    #create 6 random materials
    create_materials()
    
    #create and assign selection tag
    tags = create_poly_selection(op)
    if not assign_selection(op, tags):
        return
    
    #create texture tag into the obj
    create_texture_tag(op, tags)
    
    doc.EndUndo()
    c4d.EventAdd()

if __name__=='__main__':
    main()

anyway to get a list of empty selection tags that has no materials assigned to it ?
also the Materials that are assigned to an object but its not attached to any selection
i face this issue almost everytime i combine objects , often materials/selections get duplicated
specially on large objects with a lot of materials