SimSiam

This is an Unofficial PyTorch implementation of Exploring Simple Siamese Representation Learning [1]. It is highly inspired by PatrickHua's repository. The key features in this repository are

1. It supports DistributedDataParallel (DDP) -- not the old fashion DataParallel
2. It separates the loss function (criteria) from the model. Thus, it is easier to modify the loss function (e.g., add a regularizer) without changing the model.
3. It automatically switches between the CIFAR-ResNet and the official ResNet based on the training dataset.
4. The code supports both CIFAR10 and CIFAR100

Requirements

• Python 3+ [Tested on 3.7]
• PyTorch 1.x [Tested on 1.7.1]

Usage example

First update constants.py with your dataset dir and checkpoints dir

To train a model python pretrain_main.py

To train a linear classifier python classifier_main.py -- Make sure to update the path of the pretrained model before running.

The CIFAR hyperparameters are already hard coded in the python script. However these hyperparameters can be overridden by providing at least one parameter when running the script (e.g., python pretrain_main.py --arch SimCLR)

By default the code leverage DistributedDataParallel. The are two key parameters to identify the training GPUs

• --world_size denotes how many GPUs to use
• --base_gpu denotes what is the start GPU index (0-based).

For example if a machine has four GPUs, and user sets world_size=3 and base_gpu=1, the model will be trained on the 2nd, 3rd and 4th GPUs.

The code logs the training progress in two files

• train_X.log: Assuming base_gpu=X, the file contains text log of the training progress. There are sample log files inside ./sample_runs dir. These are complete/incomplete runs.
• exp_name.csv: This csv file keeps track of the KNN accuracy at each --test_interval

To train simCLR model, change the arch parameter to simCLR. This code achieves 89.56% KNN accuracy with simCLR (check ./sample_runs dir).

Quantitative Evaluation on CIFAR10

	Paper [1]	Ours
KNN Accracy
Linear Classifier	91.8	90.27

Release History

• 1.0.0
  • First commit on 8 Jan 2021

TODO LIST

• Revise the readme file
• Test pretrain_main.py with SimCLR
• Add the classifier_main.py

References

[1] Chen, Xinlei and He, Kaiming. Representation Learning by Learning to Count. arXiv preprint arXiv:2011.10566