Hey Arnab,
Thanks for your interest!
If you are looking for just the backend parts of tpot, you can access the raw tpot object in an automatminer pipeline through the MatPipe.learner.backend attribute. This is a raw TPOTClassifier/TPOTRegressor object and should have all API components in the regular TPOT library (completely separate from automatminer). From this object you should be able to export the optimized pipeline.
For pausing a pipeline, this is something that is a current issue on the Github repo, but we haven't gotten around to fixing yet. If you have an idea for how best to go about this, we welcome code contributions, please make a PR!
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On a separate note, as automatminer is still in an experimental phase (especially in regard to presets), we are not making any guarantees about the "production" preset. While it should work well enough, if it doesn't (or if there is something you want to change about it, i.e., the optimization time), I'd recommend specifying your own custom MatPipe. We have some docs and tutorials for that in the works, but in the meantime if you need help with that, feel free to ask on this board.
Thanks,
Alex