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ChroMOO (or chromoo)

Chromatography optimization with cadet and pymoo. I built this because CADET-Match didn't offer optimization with certain parameters and objectives. For example, optimizing SOLUTION_BULK is not possible currently. Input of vector parameters is also currently not possible.

While I haven't yet fully looked through the source code of CADET-Match, I would like to take inspiration from it while building chromoo. Eventually, when I get a better understanding of pymoo, CADET-Match and the problem, I believe it should be possible to merge the code into CADET-Match.

Installation

# Install cadet. This can be done via conda as below 
# or directly from source https://github.com/modsim/CADET
conda config --add channels conda-forge
conda config --set channel_priority strict
conda install cadet

# Install python dependencies
pip install -r requirements.txt

# Install this package. Use -e for an editable install.
pip install .

Usage

Chromoo requires a YAML config file. I use ruamel.yaml, which allows using YAML v1.2, meaning comments are allowed, and exponential notation is better parsed.

A template of the config follows:

filename: 10k-mono.mono1d.h5
load_checkpoint: checkpoint.npy
force_checkpoint_continue: false
nproc: 4
store_temp: false
transforms: 
  parameters: lognorm
  objectives: geometric
parameters:
    - name: axial
      length: 1
      path: input.model.unit_002.col_dispersion
      min_value: 1.0e-9
      max_value: 1.0e-4
objectives: 
    - name: outlet
      filename: chromatogram-from-xns.csv
      # times: timesteps.txt
      score: sse
      path: output.solution.unit_003.solution_outlet_comp_000
algorithm: 
  name: nsga3
  pop_size: 10
termination:
  x_tol: 1e-8
  cv_tol: 1e-6
  f_tol: 1e-9
  nth_gen: 2
  n_last: 10
  n_max_gen: 10
  n_max_evals: 100000

Notes

  • It runs multiple cadet simulations from a pool size of nproc for every evaluation of a population.
  • parameters and objectives are lists
  • Objective targets can be provided as an (times,values) csv file in objectives.filename or with the times separately specified in objectives.times
    • chromatograms already contain times, so it's easier to just provide the filename
    • solution_bulk data obtained from 3D sims are multidimensional, and we would like to try fitting the whole thing as a flat vector first
  • The solution_times section of the provided cadet simulation will be changed to match those of objectives[0] exactly.
  • Recommended population sizes for n-dimensional problems is 100*n
  • [CRIT] Don't fit porosity and velocity together. You can fit porosity and flowrate instead
  • Provided examples, while valid, are NOT guaranteed to be correct. Though I will try to keep them correct.
  • Checkpoints are saved at every generation by default. Checkpoints help avoid the pain of libpthread (or other) crashes from having to completely restart the fitting.
  • Use force_checkpoint_continue to force the algorithm to continue from a terminated checkpoint. Helpful if you made the termination criteria stricter.
  • Be careful when resuming from a checkpoint. Any changes to problem parameters might not be reflected because the algorithm/problem is fully restored from the checkpoint
  • transforms.parameters (choices = [lognorm, norm, none]) applies to all inputs individually
  • transforms.objectives (choices = [none, mean, geometric]) will be made to convert multiple objectives into a single objective.

Known Issues

  • [CRIT] Got simulation failure due to error 4 in libpthread (see dmesg when it happens) on IBT012. Simulation runs manually.
  • Reading inputs from YAML loads strings as str and from h5 files we get numpy.bytes_. CADET-Python run_load() uses load_results() instead of full load(). So if we check for input string values after simulation, the type of it depends on whether we use full load() or load_results() since we deal with YAML files as well. So we have to consider whether we deal with strings or bytestrings. Simple solution: Don't use run_load in scripts.
  • Loading checkpoints also loads the previous values for all/most parameters. So if nproc is updated before loading, the new value isn't used.

TODO

  • [ONGO] Move to numpy arrays
  • [CRIT] Hypervolume indicator as a convergence criterion
  • [DONE] Replace readArray, readChromatogram with np.genfromtxt or loadtxt
  • [DONE] Implement Objective vs Objective 2D plots
  • [TASK] Adjust Verbose Display according to algorithm used
  • [TASK] Random seeds
  • [TASK] Make sure tests delete temp files
  • [TASK] Write unit tests for all classes
  • [TASK] Write a configHandler method to output a dummy config.
  • [CRIT] For the split-chromatogram problem, we know that the axial dispersion in once radial shell won't affect the chromatogram in another, so it does have a constraint. Is there a way to constrain the parameters that way? Or does it just mean we solve the system serially?
  • [TASK] Unified interface/method for deep getting and setting from/to a Dict or dict
  • [TASK] Fix typings for configHandler attributes
  • [DONE] Pickle pop xs and fs for use with chromoo-post
  • [TASK] Own pareto front
  • [TASK] chromoo-post: plots
    • [DONE] objectives vs objectives: corner
    • [DONE] ALL parameters_objectives plots (as subplots and separate)
    • [TASK] Best per generation (opts)
    • [TASK] Best per generation (pops)
    • [TASK] Best ever
  • [TASK] Consider weighting objectives: Look at weighted least squares
  • [TASK] Consider multi-started/restarted systems
  • [TASK] Check out numpickle: https://gwang-jin-kim.medium.com/faster-loading-and-saving-of-pandas-data-frames-using-numpickle-numpy-and-pickle-d15870519529
  • Performance of np.take() with numbajit vs boolean indexing: https://stackoverflow.com/questions/46041811/performance-of-various-numpy-fancy-indexing-methods-also-with-numba
  • Improved plotting for large number of subplots in post: https://stackoverflow.com/questions/13046127/matplotlib-very-slow-is-it-normal/13060980#13060980
  • [CRIT] Check for behavior when take=[2,[0,1,2...]]. i.e., when indices is a list. Does verify fail? What happens?
  • [TASK] Look into all the uses of .squeeze() and simplify everything. We probably use it to squeeze out the ncomp dimension which we don't need and is always 1.