Potential bug saving parametric ROM class.

[eparish1]

Describe the bug I am trying to save an "InterpolatedContinuousOpInfROM" I have fit to file. There seems to be an issue with the save function here. When I try and save, I get an error about a LinearOperator object not having the parameters attribute.

To Reproduce

import numpy as np
import opinf

N = 10
K = 5
n_snaps = 8
Phi = np.random.normal(size=(N,K))
states = np.random.normal(size=(N,n_snaps))
states_dot = np.random.normal(size=(N,n_snaps))
params = np.array([1])
rom = opinf.InterpolatedContinuousOpInfROM("A", InterpolatorClass='auto')
rom.fit(Phi,parameters=params, states=[states], ddts=[states_dot])
rom.save('my_model.h5',overwrite=True)

Expected behavior From the documentation, it looks like the model should save and then be loadable.

Output Traceback (most recent call last): File "test_save.py", line 13, in rom.save('my_model.h5',overwrite=True) File "/Users/ejparis/.local/lib/python3.9/site-packages/opinf/roms/interpolate/_base.py", line 382, in save hf.createdataset(f"operators/{key}", data=op.matrices) File "/Users/ejparis/.local/lib/python3.9/site-packages/opinf/roms/interpolate/_base.py", line 381, in save hf.create_dataset("parameters", data=op.parameters) AttributeError: 'LinearOperator' object has no attribute 'parameters'

Additional context I have no issues in the non-parametric context.

[shanemcq18]

Thanks for sharing @eparish1, I'll take a look at this.

[shanemcq18]

Error occurs here:

# src/opinf/roms/interpolate/_base.py

class _InterpolatedOpInfROM(_BaseParametricROM):
    # ...
    def save(self, savefile, save_basis=True, overwrite=False):
        # ...
        with hdf5_savehandle(savefile, overwrite=overwrite) as hf:
            # ...
            for key, op in zip(self.modelform, self):
                if "parameters" not in hf:
>                   hf.create_dataset("parameters", data=op.parameters)

The for loop has a single iteration with key = "A" and op = self.A_. Here op is assumed to be an InterpolatedLinearOperator (which has a parameters attribute), but in this case it's a (non-parametric) LinearOperator because there is only one parameter value (i.e., no interpolation).

# src/opinf/roms/interpolate/_base.py

class _InterpolatedOpInfROM(_BaseParametricROM):
    # ...
    def _interpolate_roms(self, parameters, roms):
        # ...
        for key in self.modelform:
            attr = f"{key}_"
            ops = [getattr(rom, attr).entries for rom in roms]
>           if all(np.all(ops[0] == op) for op in ops):
>               # This operator does not depend on the parameters.
>               OperatorClass = operators.nonparametric_operators[key]
>               setattr(self, attr, OperatorClass(ops[0]))
            else:
                # This operator varies with the parameters (so interpolate).
                OperatorClass = operators.interpolated_operators[key]
                setattr(self, attr, OperatorClass(parameters, ops,
                                                  self.InterpolatorClass))

The fact that A_ is a LinearOperator is fine, but the save() method needs to be updated to handle nonparametric operators. The load() method may also have the same issue.

(Note to self: the operator-centric refactor should prevent issues like this)

[eparish1]

Nice, thanks Shane!