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Neural Sheaf Diffusion

This repository contains the official code for the paper Neural Sheaf Diffusion: A Topological Perspective on Heterophily and Oversmoothing in GNNs (NeurIPS 2022).

Getting started

We used CUDA 10.2 for this project. To set up the environment, run the following command:

conda env create --file=environment_gpu.yml
conda activate nsd

For using another CUDA version, modify the version specified inside environment_gpu.yml. If you like to run the code in a CPU-only environment, then use environment_cpu.

To make sure that everything is set up correctly, you can run all the tests using:

pytest -v .

Running experiments

To run the experiments without a Weights & Biases (wandb) account, first disable wandb by running wandb disabled. Then, for instance, to run the training procedure on texas, simply run the example script provided:

sh ./exp/scripts/run_texas.sh

To run the experiments using wandb, first create a Weights & Biases account. Then run the following commands to log in and follow the displayed instructions:

wandb online
wandb login

Then, you can run the example training procedure on texas via:

export ENTITY=<WANDB_ACCOUNT_ID>
sh ./exp/scripts/run_texas.sh

Scripts for the other heterophilic datasets are also provided in exp/scripts.

Hyperparameter Sweeps

To run a hyperparameter sweep, you will need a wandb account. Once you have an account, you can run an example sweep as follows:

export ENTITY=<WANDB_ACCOUNT_ID>
wandb sweep --project sheaf config/orth_webkb_sweep.yml

This will set up the sweep for a discrete bundle model on the WebKB datasets as described in the yaml config at config/orth_webkb_sweep.yml.

To run the sweep on a single GPU, simply run the command displayed on screen after running the sweep command above. If you like to run the sweep on multiple GPUs, then run the following command by typing in the SWEEP_ID received above.

sh run_sweeps.sh <SWEEP_ID>

Datasets

The WebKB (texas, wisconsin, cornell) and film datasets are downloaded on the fly. The WikipediaNetwork datasets with the Geom-GCN pre-processing can be downloaded from the Geom-GCN repo. The files for the Planetoid datasets can also be found in the Geom-GCN repo. The downloaded files must be placed into datasets/<DATASET_NAME>/raw/.

Credits

For attribution in academic contexts, please use the bibtex entry below:

@inproceedings{
 bodnar2022neural,
 title={Neural Sheaf Diffusion: A Topological Perspective on Heterophily and Oversmoothing in {GNN}s},
 author={Cristian Bodnar and Francesco Di Giovanni and Benjamin Paul Chamberlain and Pietro Li{\`o} and Michael M. Bronstein},
 booktitle={Advances in Neural Information Processing Systems},
 editor={Alice H. Oh and Alekh Agarwal and Danielle Belgrave and Kyunghyun Cho},
 year={2022},
 url={https://openreview.net/forum?id=vbPsD-BhOZ}
}