Issue in _calculate_model_delta() in federatedscope/core/workers /client.py

[Pengxin-Guo]

The _calculate_model_delta() may need to be modified to the code below to satisfy running pFL, since the updated_model is a subset of the init_model:

def _calculate_model_delta(self, init_model, updated_model):
    if not isinstance(init_model, list):
        init_model = [init_model]
        updated_model = [updated_model]

    model_deltas = list()
    for model_index in range(len(init_model)):
        # model_delta = copy.deepcopy(init_model[model_index])
        # for key in init_model[model_index].keys():
        #     model_delta[key] = updated_model[model_index][
        #         key] - init_model[model_index][key]
        
        # added by me, for pFL
        model_delta = copy.deepcopy(updated_model[model_index])
        for key in updated_model[model_index].keys():
            model_delta[key] = updated_model[model_index][
                key] - init_model[model_index][key]
        model_deltas.append(model_delta)

    if len(model_deltas) > 1:
        return model_deltas
    else:
        return model_deltas[0]