import bpy

#make sure we only have 2 objects selected
if len(bpy.context.selected_objects) == 2:
    
    #get target and source objects
    first_object = bpy.context.selected_objects[0]
    second_object = bpy.context.selected_objects[1]
    
    #get target and source mesh objects
    
    has_active_target = False
    
    if first_object ==  bpy.context.view_layer.objects.active:
        target_object = first_object
        target_mesh = first_object.data
        
        source_object = second_object
        source_mesh = second_object.data
        
        has_active_target = True
    
    elif second_object == bpy.context.view_layer.objects.active:
        target_object = second_object
        target_mesh = second_object.data
        
        source_object = first_object
        source_mesh = first_object.data

        has_active_target = True
        
    else:
        print ("One object needs to be active")
        has_active_target = False
    

    if has_active_target == True:

        print ("Source : " + source_mesh.name)
        print ("Target : " + target_mesh.name)
    
        #create new list with only the selected verts from each object in it
        source_selected_verts = list(filter(lambda v: v.select, source_mesh.vertices))
        target_selected_verts = list(filter(lambda v: v.select, target_mesh.vertices))
        
        #create int list of target verts selected
        target_selected_verts_index = [i.index for i in target_selected_verts]
        
        #make sure we only have one source vert selected
        if len(source_selected_verts) == 1:
            
            #get selected single vert
            source_selected_vert = source_selected_verts[0]
            
            #get vertex index
            source_selected_verts_index = source_selected_vert.index
            
            #get all the group names in the source object
            vgroup_names = {vgroup.index: vgroup.name for vgroup in source_object.vertex_groups}
            
            #iterate through all the vertex associated with the object and create a look up list
            vgroups = {v.index: [vgroup_names[g.group] for g in v.groups] for v in source_mesh.vertices}
            

            #get count of source groups
            for i in range (len(vgroups[source_selected_verts_index])):
                
                #get group name string
                group_name = vgroups[source_selected_verts_index][i]
                
                #get weight for that group
                group_weight = source_selected_vert.groups[i].weight
                
                #remove any groups from the destination mesh
                for vgroup in target_object.vertex_groups:
                    if vgroup.name ==  group_name:   
                        target_object.vertex_groups.remove(vgroup)
                
                #create new group
                new_group = target_object.vertex_groups.new(name=group_name)
                
                #use selected target index range to add weight
                new_group.add(target_selected_verts_index,group_weight,'ADD')
        
        print ("Vertex weights copied")
    else:
        print ("Only select one source vertex to copy from")
else:
    print ("Only select 2 objects")