This repository is the official PyTorch implementation of:

DENSE: Data-Free One-Shot Federated Learning (NeurIPS 2022).

• This codebase is written for python3 (used python 3.6 while implementing).
• We use Pytorch version of 1.8.2, 11.4 CUDA version.
• To install necessary python packages,

pip install -r requirements.txt

• The logs are uploaded to the wandb server. If you do not have a wandb account, just install and use as offline mode.

pip install wandb
wandb off

At first, we divide the data into $m$ clients, train the model on each client until it converges and send it to the central server. The sample code is as follows:

python3 loop_df_fl.py --type=pretrain  --iid=0 --lr=0.01 --model=cnn \
--dataset=cifar10 --beta=0.5 --seed=1 --num_users=5 --local_ep=400

Here is an explanation of some parameters,

• --dataset: name of the datasets (e.g., mnist, cifar10, cifar100 or cinic10).
• --num_users: the number of total clients (e.g., 5, 20, 100).
• --batch_size: the size of batch to be used for local training. (default: 256)
• --iid: IID or non-IID partition strategy (0 for non-IID).
• --beta: concentration parameter beta for latent Dirichlet Allocation (default: beta=0.5).
• --model: model architecture to be used (e.g., cnn, resnet, or vit).
• --epochs: the number of total communication rounds. (default: 200)
• --frac: fraction of clients to be ramdonly sampled at each round (default: 1)
• --local_ep: the number of local epochs (default: 400).
• --lr: the initial learning rate for local training (default: 0.01)
• --momentum: the momentum for SGD (default: 0.9).
• --seed: random seed
• --adv: scaling factor for adv loss
• --bn: scaling factor for BN regularization
• --lr_g: learning rate for the generator

Note that the same random seed must be fixed for fair comparison. Because different random seeds mean that the data distribution on each client is different. Therefore, we should use several random seeds in the experiments. For args.seed=1. Here is an example for --seed=1 (cifar10, 5 clients, $beta$=0.5),

Data statistics: {client 0: {0: 156, 1: 709, 2: 301, 3: 2629, 4: 20, 5: 651, 6: 915, 7: 113, 8: 180, 9: 2133}, \
client 1: {0: 1771, 1: 2695, 2: 1251, 3: 1407, 4: 665, 5: 314, 6: 1419, 7: 3469}, \
client 2: {0: 236, 1: 15, 2: 1715, 3: 76, 4: 1304, 5: 34, 6: 1773, 7: 75, 8: 3289, 9: 2360}, \
client 3: {0: 2809, 1: 575, 2: 157, 3: 853, 4: 2555, 5: 2557, 6: 203, 7: 1213}, \
client 4: {0: 28, 1: 1006, 2: 1576, 3: 35, 4: 456, 5: 1444, 6: 690, 7: 130, 8: 1531, 9: 507}}

The sample learning curves for local training:

The accuracy for model ensemble (teacher) and the accuracy after FedAvg:

For each client, Accuracy: 55 / 55 / 59 / 60 / 62
FedAvg Accuracy: 30.9300
Ensemble Accuracy: 71.8100

Then we use the ensemble of local models for KD. Here is the sample code,

python loop_df_fl.py --type=kd_train --iid=0 --epochs=200 --lr=0.005 --batch_size 256 --synthesis_batch_size=256 \
--g_steps 30 --lr_g 1e-3 --bn 1.0 --oh 1.0 --T 20 --save_dir=run/cifar10 --other=cifar10 --model=cnn --dataset=cifar10 \
--adv=1 --beta=0.5 --seed=1

Note that the parameters are not well-designed in the experiments, intuitively the accuracy of KD should be close to the performance of the model ensemble.

The synthetic data for one batch (CIFAR10):

@inproceedings{zhangdense,
  title={DENSE: Data-Free One-Shot Federated Learning},
  author={Zhang, Jie and Chen, Chen and Li, Bo and Lyu, Lingjuan and Wu, Shuang and Ding, Shouhong and Shen, Chunhua and Wu, Chao},
  booktitle={Advances in Neural Information Processing Systems}
}