Operator Inference in Python

This is a Python implementation of Operator Inference for learning projection-based polynomial reduced-order models of dynamical systems. The procedure is data-driven and non-intrusive, making it a viable candidate for model reduction of "glass-box" systems. The methodology was introduced in [1].

See the Wiki for mathematical details and API documentation. See this repository for a MATLAB implementation.

Quick Start

Installation

Install the package from the command line with the following single command (requires pip).

$ python3 -m pip install --user rom-operator-inference

See the wiki for other installation options.

Usage

Given a basis matrix Vr, snapshot data Q, and snapshot time derivatives Qdot, the following code learns a reduced-order model for a problem of the form dq / dt = c + Aq(t), then solves the reduced system for 0 ≤ t ≤ 1.

import numpy as np
import rom_operator_inference as opinf

# Define a reduced-order model of the form  dq / dt = c + Aq(t).
>>> rom = opinf.InferredContinuousROM(modelform="cA")

# Fit the model to snapshot data Q, the time derivatives Qdot,
# and the linear basis Vr by solving for the operators c_ and A_.
>>> rom.fit(Vr, Q, Qdot)

# Simulate the learned model over the time domain [0,1] with 100 timesteps.
>>> t = np.linspace(0, 1, 100)
>>> Q_ROM = rom.predict(Q[:,0], t)

Contributors: Shane McQuarrie, Renee Swischuk, Elizabeth Qian, Boris Kramer, Karen Willcox.

References

These publications introduce, build on, or use Operator Inference. Entries are listed chronologically.

• [1] Peherstorfer, B. and Willcox, K., Data-driven operator inference for non-intrusive projection-based model reduction. Computer Methods in Applied Mechanics and Engineering, Vol. 306, pp. 196-215, 2016. (Download)

  BibTeX

  @article{PW2016OperatorInference,
  title     = {Data-driven operator inference for nonintrusive projection-based model reduction},
  author    = {Peherstorfer, B. and Willcox, K.},
  journal   = {Computer Methods in Applied Mechanics and Engineering},
  volume    = {306},
  pages     = {196--215},
  year      = {2016},
  publisher = {Elsevier}
  }

• [2] Qian, E., Kramer, B., Marques, A., and Willcox, K., Transform & Learn: A data-driven approach to nonlinear model reduction. In the AIAA Aviation 2019 Forum & Exhibition, Dallas, TX, June 2019. Paper AIAA-2019-3707. (Download)

  BibTeX

  @inbook{QKMW2019TransformAndLearn,
  title     = {Transform \& Learn: A data-driven approach to nonlinear model reduction},
  author    = {Qian, E. and Kramer, B. and Marques, A. N. and Willcox, K. E.},
  booktitle = {AIAA Aviation 2019 Forum},
  year      = {2018},
  address   = {Dallas, TX},
  note      = {Paper AIAA-2019-3707},
  doi       = {10.2514/6.2019-3707},
  URL       = {https://arc.aiaa.org/doi/abs/10.2514/6.2019-3707},
  eprint    = {https://arc.aiaa.org/doi/pdf/10.2514/6.2019-3707}
  }

• [3] Swischuk, R., Mainini, L., Peherstorfer, B., and Willcox, K., Projection-based model reduction: Formulations for physics-based machine learning. Computers & Fluids, Vol. 179, pp. 704-717, 2019. (Download)

  BibTeX

  @article{SMPW2019PhysicsbasedML,
  title     = {Projection-based model reduction: Formulations for physics-based machine learning},
  author    = {Swischuk, R. and Mainini, L. and Peherstorfer, B. and Willcox, K.},
  journal   = {Computers \& Fluids},
  volume    = {179},
  pages     = {704--717},
  year      = {2019},
  publisher = {Elsevier}
  }

• [4] Swischuk, R., Physics-based machine learning and data-driven reduced-order modeling. Master's thesis, Massachusetts Institute of Technology, 2019. (Download)

  BibTeX

  @phdthesis{swischuk2019MLandDDROM,
  title  = {Physics-based machine learning and data-driven reduced-order modeling},
  author = {Swischuk, Renee},
  year   = {2019},
  school = {Massachusetts Institute of Technology}
  }

• [5] Peherstorfer, B. Sampling low-dimensional Markovian dynamics for pre-asymptotically recovering reduced models from data with operator inference. arXiv:1908.11233. (Download)

  BibTeX

  @article{peherstorfer2019samplingMarkovian,
  title   = {Sampling low-dimensional Markovian dynamics for pre-asymptotically recovering reduced models from data with operator inference},
  author  = {Peherstorfer, Benjamin},
  journal = {arXiv preprint arXiv:1908.11233},
  year    = {2019}
  }

• [6] Swischuk, R., Kramer, B., Huang, C., and Willcox, K., Learning physics-based reduced-order models for a single-injector combustion process. AIAA Journal, Vol. 58:6, pp. 2658-2672, 2020. Also in Proceedings of 2020 AIAA SciTech Forum & Exhibition, Orlando FL, January, 2020. Paper AIAA-2020-1411. Also Oden Institute Report 19-13. (Download)

  BibTeX

  @article{SKHW2020ROMCombustion,
  title     = {Learning physics-based reduced-order models for a single-injector combustion process},
  author    = {Swischuk, R. and Kramer, B. and Huang, C. and Willcox, K.},
  journal   = {AIAA Journal},
  volume    = {58},
  number    = {6},
  pages     = {2658--2672},
  year      = {2020},
  publisher = {American Institute of Aeronautics and Astronautics}
  }

• [7] Qian, E., Kramer, B., Peherstorfer, B., and Willcox, K., Lift & Learn: Physics-informed machine learning for large-scale nonlinear dynamical systems. Physica D: Nonlinear Phenomena, Vol. 406, May 2020, 132401. (Download)

  BibTeX

  @article{QKPW2020LiftAndLearn,
  title   = {Lift \& Learn: Physics-informed machine learning for large-scale nonlinear dynamical systems.},
  author  = {Qian, E. and Kramer, B. and Peherstorfer, B. and Willcox, K.},
  journal = {Physica {D}: {N}onlinear {P}henomena},
  volume  = {406},
  pages   = {132401},
  url     = {https://doi.org/10.1016/j.physd.2020.132401},
  year    = {2020}
  }

• [8] Benner, P., Goyal, P., Kramer, B., Peherstorfer, B., and Willcox, K., Operator inference for non-intrusive model reduction of systems with non-polynomial nonlinear terms. arXiv:2002.09726. Also Oden Institute Report 20-04. (Download)

  BibTeX

  @article{BGKPW2020OpInfNonPoly,
  title   = {Operator inference for non-intrusive model reduction of systems with non-polynomial nonlinear terms},
  author  = {Benner, P. and Goyal, P. and Kramer, B. and Peherstorfer, B. and Willcox, K.},
  journal = {arXiv preprint arXiv:2002.09726},
  year    = {2020}
  }

• [9] Yıldız, S., Goyal, P., Benner, P., and Karasözen, B., Data-driven learning of reduced-order dynamics for a parametrized shallow water equation. arXiv:2007.14079. (Download)

  BibTeX

  @article{SGBK2020OpInfAffine,
  title   = {Data-Driven Learning of Reduced-order Dynamics for a Parametrized Shallow Water Equation},
  author  = {Y{\i}ld{\i}z, S. and Goyal, P. and Benner, P. and Karas{\"o}zen, B.},
  journal = {arXiv preprint arXiv:2007.14079},
  year    = {2020}
  }

• [10] McQuarrie, S. A., Huang, C., and Willcox, K., Data-driven reduced-order models via regularized operator inference for a single-injector combustion process. arXiv:2008.02862. (Download)

  BibTeX

  @article{MHW2020regOpInfCombustion,
  title   = {Data-driven reduced-order models via regularized operator inference for a single-injector combustion process},
  author  = {McQuarrie, S. A. and Huang, C. and Willcox, K.},
  journal = {arXiv preprint arXiv:2008.02862},
  year    = {2020}
  }