Sparse OPTimisation Library

Description

SOPT is an open-source C++ package available under the license below. It performs Sparse OPTimisation using state-of-the-art convex optimisation algorithms. It solves a variety of sparse regularisation problems, including the Sparsity Averaging Reweighted Analysis (SARA) algorithm.

SOPT also has several MPI wrappers that can be adapted for computational distirbution of various linear operators and convex optimisation algorithms. Wavelet Operators with SOPT also support multi-threading through OpenMP.

SOPT is written in C++ primarily but also contains partial and prototyped Matlab implementations of various algorithms.

SOPT is largely provided to support the PURIFY package, a companion open-source code to perform radio interferometric imaging, also written by the authors of SOPT. For further background please see the reference section.

This documentation outlines the necessary and optional dependencies upon which SOPT should be built, before describing installation and testing details and Matlab support. Contributors, references and license information then follows.

Dependencies installation

SOPT is mostly written in C++17. Pre-requisites and dependencies are listed in following and minimal versions required are tested against Travis CI meaning that they come natively with OSX and the Ubuntu Trusty release. These are also the default ones fetched by CMake.

C++ minimal dependencies:

• CMake v3.9.2 A free software that allows cross-platform compilation.
• GCC v7.3.0 GNU compiler for C++.
• OpenMP v4.8.4 (Trusty) - Optional - Speeds up some of the operations.
• Eigen3 v3.4.0 (Trusty) Modern C++ linear algebra. Downloaded automatically if absent.
• Catch2 v3.4.0 - Optional - A C++ unit-testing framework only needed for testing.
• google/benchmark - Optional - A C++ micro-benchmarking framework only needed for benchmarks.
• tiff v4.5.1 (Trusty) Tag Image File Format library - only installed if needed.
• ONNXruntime v1.17.1 - Optional - a cross-platform runtime engine based on the Open Neural Network eXchange format.

Installing and building SOPT

If the dependencies are already available on your system, you can install SOPT manually like so

bash cd /path/to/code mkdir build cd build cmake .. -DCMAKE_INSTALL_PREFIX=${PWD}/../local make -j make -j install

On MacOS, you can also install most of the dependencies with Homebrew e.g.

bash brew install libtensorflow eigen tiff catch2 Note that on MacOS, the ONNXruntime currently only support Clang but not g++

Testing

To check everything went all right, run the test suite:

bash cd /path/to/code/build ctest .

Debugging the CI workflow with tmate

The CI workflow has a manual dispatch trigger which allows you to log into the job while it's running. You can trigger it in actions. Run the workflow and set debug_enabled=true to enable the tmate step in the CI workflow. Once the workflow is running, open the job in actions. You should see it printing out a line with a ssh command. Run it in terminal to log into the GitHub Actions runner.

Machine-learning models

Machine-learning models are supported via the ONNXruntime interface. Nearly all modern ML toolkits allow to export their trained models into the ONNXruntime format using Python.

Install translation packages e.g. using pip: pip install onnx pip install onnxscript

PyTorch models can be exported to ONNXruntime like so import torch torch_model = ... # PyTorch model based on torch.nn torch_input = torch_input = torch.randn(256, 256) # model input tensor torch.onnx.export(torch_model, torch_init, 'model_name.onnx', # output file name export_params=True, # store trained param weights opset_version=11, # ONNX version to export the model to do_constant_folding=True, # optmise using pre-computed constant nodes input_names=['input'], output_names=['ouput'], dynamic_axes={'input' : {0 : 'batch_size'}, 'output' : {0 : 'batch_size'}})

Tensorflow models can be exported to ONNXruntime like so python -m tf2onnx.convert --saved-model model_name.pb --output model_name.onnx --opset 11 --inputs input0:0 --extra_opset StatefulPartitionedCall:0

After the export, load the model and verify that it's well formed like so import onnx onnx_model = onnx.load("model_name.onnx") onnx.checker.check_model(onnx_model) print( onnx_model.graph.input ) Hard-coded dimensions can be removed from the input/output tensor e.g. like so print (onnx_model.graph.input[0].type.tensor_type.shape) onnx_model.graph.input[0].type.tensor_type.shape.dim[1].ClearField('dim_value')

Netron is a useful online tool to help visualise the model.

Matlab

A separate Matlab implementation is provided with SOPT. This implementation includes some (but not all) of the optimisation algorithms implemented in the C++ code, including the SARA algorithm.

The Matlab implementation is contained in the matlab directory. This is a stand-alone implementation and does not call any of the C++ code. In future, Matlab interfaces to the C++ code may also be included in SOPT.

See matlab/README.txt for an overview of the Matlab implementation. The stand-alone Matlab implementation is also self-documenting; corresponding documentation can be found in matlab/doc. We thank Gilles Puy for contributing to this Matlab implementation.

Contributors

Check the contributors page (github).

References and citation

If you use SOPT for work that results in publication, please reference the webpage and our related academic papers:

1. L. Pratley et al. (to be published)
2. A. Onose, R. E. Carrillo, A. Repetti, J. D. McEwen, J.-P. Thiran, J.-C. Pesquet, and Y. Wiaux. "Scalable splitting algorithms for big-data interferometric imaging in the SKA era" Mon. Not. Roy. Astron. Soc. 462(4):4314-4335 (2016) arXiv:1601.04026
3. R. E. Carrillo, J. D. McEwen, D. Van De Ville, J.-P. Thiran, and Y. Wiaux. "Sparsity averaging for compressive imaging" IEEE Signal Processing Letters 20(6):591-594 (2013) arXiv:1208.2330
4. R. E. Carrillo, J. D. McEwen and Y. Wiaux. "Sparsity Averaging Reweighted Analysis (SARA): a novel algorithm for radio-interferometric imaging" Mon. Not. Roy. Astron. Soc. 426(2):1223-1234 (2012) arXiv:1205.3123

License

SOPT: Sparse OPTimisation package Copyright (C) 2013-2024

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details (LICENSE.txt).

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

Webpage

• Documentation
• Repository

Support

For any questions or comments, feel free to contact Jason McEwen, or add an issue to the issue tracker.

Notes

The code is given for educational purpose. For the Matlab version of the code see the folder matlab.