Papers › PaddingFlow: Improving Normalizing Flows with Padding-Dimensional Noise

PaddingFlow: Improving Normalizing Flows with Padding-Dimensional Noise

13 Mar 2024arXiv:2403.08216archive 2025-07-28

Qinglong Meng, Chongkun Xia, Xueqian Wang

Normalizing flow is a generative modeling approach with efficient sampling. However, Flow-based models suffer two issues: 1) If the target distribution is manifold, due to the unmatch between the dimensions of the latent target distribution and the data distribution, flow-based models might perform badly. 2) Discrete data might make flow-based models collapse into a degenerate mixture of point masses. To sidestep such two issues, we propose PaddingFlow, a novel dequantization method, which improves normalizing flows with padding-dimensional noise. To implement PaddingFlow, only the dimension of normalizing flows needs to be modified. Thus, our method is easy to implement and computationally cheap. Moreover, the padding-dimensional noise is only added to the padding dimension, which means PaddingFlow can dequantize without changing data distributions. Implementing existing dequantization methods needs to change data distributions, which might degrade performance. We validate our method on the main benchmarks of unconditional density estimation, including five tabular datasets and four image datasets for Variational Autoencoder (VAE) models, and the Inverse Kinematics (IK) experiments which are conditional density estimation. The results show that PaddingFlow can perform better in all experiments in this paper, which means PaddingFlow is widely suitable for various tasks. The code is available at: https://github.com/AdamQLMeng/PaddingFlow.

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Code

adamqlmeng/paddingflow officialmentioned in papermentioned on GitHubpytorch report

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Tasks

Density Estimation

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Density Estimation BSDS300 PaddingFlow CD 0.495 #5 of 5 Archive leaderboard report
Density Estimation BSDS300 PaddingFlow EMD 0.0248 #5 of 5 Archive leaderboard report
Density Estimation BSDS300 PaddingFlow MMD-CD 0.48 #5 of 5 Archive leaderboard report
Density Estimation BSDS300 PaddingFlow MMD-EMD 0.0212 #5 of 5 Archive leaderboard report
Density Estimation Caltech-101 PaddingFlow COV-L2 98.7% #3 of 3 Archive leaderboard report
Density Estimation Caltech-101 PaddingFlow MMD-L2 17.9 #3 of 3 Archive leaderboard report
Density Estimation Freyfaces PaddingFlow COV-L2 100% #3 of 3 Archive leaderboard report
Density Estimation Freyfaces PaddingFlow MMD-L2 0.621 #3 of 3 Archive leaderboard report
Density Estimation MNIST PaddingFlow COV-L2 100% #4 of 6 Archive leaderboard report
Density Estimation MNIST PaddingFlow MMD-L2 11.0 #4 of 6 Archive leaderboard report
Density Estimation OMNIGLOT PaddingFlow COV-L2 98.8% #4 of 4 Archive leaderboard report
Density Estimation OMNIGLOT PaddingFlow MMD-L2 20.3 #4 of 4 Archive leaderboard report
Density Estimation UCI GAS PaddingFlow CD 0.89 #5 of 5 Archive leaderboard report
Density Estimation UCI GAS PaddingFlow EMD 0.131 #5 of 5 Archive leaderboard report
Density Estimation UCI GAS PaddingFlow MMD-CD 0.39 #5 of 5 Archive leaderboard report
Density Estimation UCI GAS PaddingFlow MMD-EMD 0.121 #5 of 5 Archive leaderboard report
Density Estimation UCI HEPMASS PaddingFlow CD 13.8 #2 of 5 Archive leaderboard report
Density Estimation UCI HEPMASS PaddingFlow EMD 0.161 #2 of 5 Archive leaderboard report
Density Estimation UCI HEPMASS PaddingFlow MMD-CD 13.7 #2 of 5 Archive leaderboard report
Density Estimation UCI HEPMASS PaddingFlow MMD-EMD 0.153 #2 of 5 Archive leaderboard report
Density Estimation UCI MINIBOONE PaddingFlow CD 24.5 #3 of 5 Archive leaderboard report
Density Estimation UCI MINIBOONE PaddingFlow EMD 0.268 #3 of 5 Archive leaderboard report
Density Estimation UCI MINIBOONE PaddingFlow MMD-CD 24.0 #3 of 5 Archive leaderboard report
Density Estimation UCI MINIBOONE PaddingFlow MMD-EMD 0.255 #3 of 5 Archive leaderboard report
Density Estimation UCI POWER PaddingFlow CD 0.142 #6 of 6 Archive leaderboard report
Density Estimation UCI POWER PaddingFlow EMD 0.105 #6 of 6 Archive leaderboard report
Density Estimation UCI POWER PaddingFlow MMD-CD 0.135 #6 of 6 Archive leaderboard report
Density Estimation UCI POWER PaddingFlow MMD-EMD 0.098 #6 of 6 Archive leaderboard report

Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.

Methods

Normalizing Flows

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