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rational_interpolant_greedy_pivoted.py
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rational_interpolant_greedy_pivoted.py
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# Copyright (C) 2018 by the RROMPy authors
#
# This file is part of RROMPy.
#
# RROMPy is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# RROMPy 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with RROMPy. If not, see <http://www.gnu.org/licenses/>.
#
from copy import deepcopy as copy
import numpy as np
from .generic_pivoted_approximant import GenericPivotedApproximant
from rrompy.reduction_methods.greedy.rational_interpolant_greedy import (
RationalInterpolantGreedy)
from rrompy.reduction_methods.greedy.generic_greedy_approximant import (
pruneSamples)
from rrompy.utilities.base.types import Np1D, HFEng, DictAny, ListAny, paramVal
from rrompy.utilities.base import verbosityManager as vbMng
from rrompy.utilities.numerical import totalDegreeN, dot
from rrompy.utilities.poly_fitting.polynomial import polyvander as pv
from rrompy.utilities.exception_manager import RROMPyAssert
from rrompy.parameter import emptyParameterList, parameterList
__all__ = ['RationalInterpolantGreedyPivoted']
class RationalInterpolantGreedyPivoted(GenericPivotedApproximant,
RationalInterpolantGreedy):
"""
ROM pivoted rational interpolant (with pole matching) computation for
parametric problems.
Args:
HFEngine: HF problem solver.
mu0(optional): Default parameter. Defaults to 0.
directionPivot(optional): Pivot components. Defaults to [0].
approxParameters(optional): Dictionary containing values for main
parameters of approximant. Recognized keys are:
- 'POD': whether to compute POD of snapshots; defaults to True;
- 'matchingWeight': weight for pole matching optimization; defaults
to 1;
- 'cutOffTolerance': tolerance for ignoring parasitic poles;
defaults to np.inf;
- 'cutOffType': rule for tolerance computation for parasitic poles;
defaults to 'MAGNITUDE';
- 'S': total number of pivot samples current approximant relies
upon;
- 'samplerPivot': pivot sample point generator;
- 'SMarginal': total number of marginal samples current approximant
relies upon;
- 'samplerMarginal': marginal sample point generator;
- 'polybasis': type of polynomial basis for pivot
interpolation; defaults to 'MONOMIAL';
- 'polybasisMarginal': type of polynomial basis for marginal
interpolation; allowed values include 'MONOMIAL', 'CHEBYSHEV'
and 'LEGENDRE'; defaults to 'MONOMIAL';
- 'greedyTol': uniform error tolerance for greedy algorithm;
defaults to 1e-2;
- 'collinearityTol': collinearity tolerance for greedy algorithm;
defaults to 0.;
- 'maxIter': maximum number of greedy steps; defaults to 1e2;
- 'refinementRatio': ratio of test points to be exhausted before
test set refinement; defaults to 0.2;
- 'nTestPoints': number of test points; defaults to 5e2;
- 'trainSetGenerator': training sample points generator; defaults
to sampler;
- 'errorEstimatorKind': kind of error estimator; available values
include 'AFFINE', 'DISCREPANCY', 'INTERPOLATORY',
'LOOK_AHEAD', and 'NONE'; defaults to 'NONE';
- 'MMarginal': degree of marginal interpolant; defaults to 0;
- 'polydegreetypeMarginal': type of polynomial degree for marginal;
defaults to 'TOTAL';
- 'radialDirectionalWeightsMarginal': radial basis weights for
marginal interpolant; defaults to 0, i.e. identity;
- 'nNearestNeighborMarginal': number of marginal nearest neighbors
considered if polybasisMarginal allows; defaults to -1;
- 'interpRcond': tolerance for pivot interpolation; defaults to
None;
- 'interpRcondMarginal': tolerance for marginal interpolation;
defaults to None;
- 'robustTol': tolerance for robust rational denominator
management; defaults to 0.
Defaults to empty dict.
approx_state(optional): Whether to approximate state. Defaults to
False.
verbosity(optional): Verbosity level. Defaults to 10.
Attributes:
HFEngine: HF problem solver.
mu0: Default parameter.
directionPivot: Pivot components.
mus: Array of snapshot parameters.
musPivot: Array of pivot snapshot parameters.
musMarginal: Array of marginal snapshot parameters.
approxParameters: Dictionary containing values for main parameters of
approximant. Recognized keys are in parameterList.
parameterListSoft: Recognized keys of soft approximant parameters:
- 'POD': whether to compute POD of snapshots;
- 'matchingWeight': weight for pole matching optimization;
- 'cutOffTolerance': tolerance for ignoring parasitic poles;
- 'cutOffType': rule for tolerance computation for parasitic poles;
- 'polybasis': type of polynomial basis for pivot
interpolation;
- 'polybasisMarginal': type of polynomial basis for marginal
interpolation;
- 'greedyTol': uniform error tolerance for greedy algorithm;
- 'collinearityTol': collinearity tolerance for greedy algorithm;
- 'maxIter': maximum number of greedy steps;
- 'refinementRatio': ratio of test points to be exhausted before
test set refinement;
- 'nTestPoints': number of test points;
- 'trainSetGenerator': training sample points generator;
- 'errorEstimatorKind': kind of error estimator;
- 'MMarginal': degree of marginal interpolant;
- 'polydegreetypeMarginal': type of polynomial degree for marginal;
- 'radialDirectionalWeights': radial basis weights for pivot
numerator;
- 'radialDirectionalWeightsMarginal': radial basis weights for
marginal interpolant;
- 'nNearestNeighbor': number of pivot nearest neighbors considered
if polybasis allows;
- 'nNearestNeighborMarginal': number of marginal nearest neighbors
considered if polybasisMarginal allows;
- 'interpRcond': tolerance for pivot interpolation;
- 'interpRcondMarginal': tolerance for marginal interpolation;
- 'robustTol': tolerance for robust rational denominator
management;
- 'correctorForce': whether corrector should forcefully delete bad
poles;
- 'correctorTol': tolerance for corrector step;
- 'correctorMaxIter': maximum number of corrector iterations.
parameterListCritical: Recognized keys of critical approximant
parameters:
- 'S': total number of pivot samples current approximant relies
upon;
- 'samplerPivot': pivot sample point generator;
- 'SMarginal': total number of marginal samples current approximant
relies upon;
- 'samplerMarginal': marginal sample point generator.
approx_state: Whether to approximate state.
verbosity: Verbosity level.
POD: Whether to compute POD of snapshots.
matchingWeight: Weight for pole matching optimization.
cutOffTolerance: Tolerance for ignoring parasitic poles.
cutOffType: Rule for tolerance computation for parasitic poles.
S: Total number of pivot samples current approximant relies upon.
samplerPivot: Pivot sample point generator.
SMarginal: Total number of marginal samples current approximant relies
upon.
samplerMarginal: Marginal sample point generator.
polybasis: Type of polynomial basis for pivot interpolation.
polybasisMarginal: Type of polynomial basis for marginal interpolation.
greedyTol: uniform error tolerance for greedy algorithm.
collinearityTol: Collinearity tolerance for greedy algorithm.
maxIter: maximum number of greedy steps.
refinementRatio: ratio of training points to be exhausted before
training set refinement.
nTestPoints: number of starting training points.
trainSetGenerator: training sample points generator.
errorEstimatorKind: kind of error estimator.
MMarginal: Degree of marginal interpolant.
polydegreetypeMarginal: Type of polynomial degree for marginal.
radialDirectionalWeightsMarginal: Radial basis weights for marginal
interpolant.
nNearestNeighborMarginal: Number of marginal nearest neighbors
considered if polybasisMarginal allows.
interpRcond: Tolerance for pivot interpolation.
interpRcondMarginal: Tolerance for marginal interpolation.
robustTol: Tolerance for robust rational denominator management.
muBoundsPivot: list of bounds for pivot parameter values.
muBoundsMarginal: list of bounds for marginal parameter values.
samplingEngine: Sampling engine.
uHF: High fidelity solution(s) with parameter(s) lastSolvedHF as
sampleList.
lastSolvedHF: Parameter(s) corresponding to last computed high fidelity
solution(s) as parameterList.
uApproxReduced: Reduced approximate solution(s) with parameter(s)
lastSolvedApprox as sampleList.
lastSolvedApproxReduced: Parameter(s) corresponding to last computed
reduced approximate solution(s) as parameterList.
uApprox: Approximate solution(s) with parameter(s) lastSolvedApprox as
sampleList.
lastSolvedApprox: Parameter(s) corresponding to last computed
approximate solution(s) as parameterList.
Q: Numpy 1D vector containing complex coefficients of approximant
denominator.
P: Numpy 2D vector whose columns are FE dofs of coefficients of
approximant numerator.
"""
def __init__(self, HFEngine:HFEng, mu0 : paramVal = None,
directionPivot : ListAny = [0],
approxParameters : DictAny = {}, approx_state : bool = False,
verbosity : int = 10, timestamp : bool = True):
self._preInit()
self._addParametersToList(toBeExcluded = ["sampler"])
super().__init__(HFEngine = HFEngine, mu0 = mu0,
directionPivot = directionPivot,
approxParameters = approxParameters,
approx_state = approx_state, verbosity = verbosity,
timestamp = timestamp)
self._postInit()
@property
def tModelType(self):
if hasattr(self, "_temporaryPivot"): return super().tModelType
from rrompy.reduction_methods.trained_model import \
TrainedModelPivotedRational
return TrainedModelPivotedRational
@property
def polybasis0(self):
if "_" in self.polybasis:
return self.polybasis.split("_")[0]
return self.polybasis
def _polyvanderAuxiliary(self, mus, deg, *args):
degEff = [0] * self.npar
degEff[self.directionPivot[0]] = deg
return pv(mus, degEff, *args)
def _marginalizeMiscellanea(self, forward:bool):
if forward:
self._m_mu0 = copy(self.mu0)
self._m_selfmus = copy(self.mus)
self._m_HFErescalingExp = copy(self.HFEngine.rescalingExp)
self._mu0 = parameterList(self.mu0(self.directionPivot))
self._mus = parameterList(self.mus(self.directionPivot))
self.HFEngine.rescalingExp = [self.HFEngine.rescalingExp[
self.directionPivot[0]]]
else:
self._mu0 = self._m_mu0
self._mus = self._m_selfmus
self.HFEngine.rescalingExp = self._m_HFErescalingExp
del self._m_mu0, self._m_selfmus, self._m_HFErescalingExp
def _marginalizeTrainedModel(self, forward:bool):
if forward:
del self._temporaryPivot
self.trainedModel.data.mu0 = self.mu0
self.trainedModel.data.scaleFactor = [1.] * self.npar
self.trainedModel.data.scaleFactor[self.directionPivot[0]] = (
self.scaleFactor[0])
self.trainedModel.data.rescalingExp = self.HFEngine.rescalingExp
Qc = np.zeros((len(self.trainedModel.data.Q.coeffs),) * self.npar,
dtype = self.trainedModel.data.Q.coeffs.dtype)
Pc = np.zeros((len(self.trainedModel.data.P.coeffs),) * self.npar
+ (self.trainedModel.data.P.coeffs.shape[1],),
dtype = self.trainedModel.data.P.coeffs.dtype)
for j in range(len(self.trainedModel.data.Q.coeffs)):
Qc[(0,) * self.directionPivot[0] + (j,)
+ (0,) * (self.npar - self.directionPivot[0] - 1)] = (
self.trainedModel.data.Q.coeffs[j])
for j in range(len(self.trainedModel.data.P.coeffs)):
for k in range(self.trainedModel.data.P.coeffs.shape[1]):
Pc[(0,) * self.directionPivot[0] + (j,)
+ (0,) * (self.npar - self.directionPivot[0] - 1)
+ (k,)] = self.trainedModel.data.P.coeffs[j, k]
self.trainedModel.data.Q.coeffs = Qc
self.trainedModel.data.P.coeffs = Pc
else:
self._temporaryPivot = 1
self.trainedModel.data.mu0 = parameterList(
self.mu0(self.directionPivot))
self.trainedModel.data.scaleFactor = self.scaleFactor
self.trainedModel.data.rescalingExp = self.HFEngine.rescalingExp[
self.directionPivot[0]]
self.trainedModel.data.Q.coeffs = self.trainedModel.data.Q.coeffs[
(0,) * self.directionPivot[0]
+ (slice(None),)
+ (0,) * (self.HFEngine.npar - 1
- self.directionPivot[0])]
self.trainedModel.data.P.coeffs = self.trainedModel.data.P.coeffs[
(0,) * self.directionPivot[0]
+ (slice(None),)
+ (0,) * (self.HFEngine.npar - 1
- self.directionPivot[0])]
self.trainedModel.data.npar = self.npar
self.trainedModel.data.Q.npar = self.npar
self.trainedModel.data.P.npar = self.npar
def errorEstimator(self, mus:Np1D, return_max : bool = False) -> Np1D:
"""Standard residual-based error estimator."""
self._marginalizeMiscellanea(True)
setupOK = self.setupApproxLocal()
self._marginalizeMiscellanea(False)
if not setupOK:
err = np.empty(len(mus))
err[:] = np.nan
if not return_max: return err
return err, 0, np.nan
self._marginalizeTrainedModel(True)
errRes = super().errorEstimator(mus, return_max)
self._marginalizeTrainedModel(False)
return errRes
def _preliminaryTraining(self):
"""Initialize starting snapshots of solution map."""
RROMPyAssert(self._mode, message = "Cannot start greedy algorithm.")
S = self.S
self.sampleBatchIdx, self.sampleBatchSize, self._S = -1, 0, 0
nextBatchSize = 1
while self._S + nextBatchSize <= S:
self.sampleBatchIdx += 1
self.sampleBatchSize = nextBatchSize
self._S += self.sampleBatchSize
nextBatchSize = totalDegreeN(self.npar - 1,
self.sampleBatchIdx + 1)
self.resetSamples()
musPivot = parameterList(self.trainSetGenerator.generatePoints(self.S)[
list(range(self.S))])
muTestPivot = self.samplerPivot.generatePoints(self.nTestPoints)
idxPop = pruneSamples(muTestPivot ** self.HFEngine.rescalingExp[
self.directionPivot[0]],
musPivot ** self.HFEngine.rescalingExp[
self.directionPivot[0]],
1e-10 * self.scaleFactor[0])
self.mus = emptyParameterList()
self.mus.reset((self.S, self.npar + len(self.musMargLoc)))
muTestBase = emptyParameterList()
muTestBase.reset((len(muTestPivot), self.npar + len(self.musMargLoc)))
for k in range(self.S):
self.mus.data[k, self.directionPivot] = musPivot[k].data
self.mus.data[k, self.directionMarginal] = self.musMargLoc.data
for k in range(len(muTestPivot)):
muTestBase.data[k, self.directionPivot] = muTestPivot[k].data
muTestBase.data[k, self.directionMarginal] = self.musMargLoc.data
muTestBase.pop(idxPop)
muTestBase = muTestBase.sort()
muLast = copy(self.mus[-1])
self.mus.pop()
if len(self.mus) > 0:
vbMng(self, "MAIN",
("Adding first {} sample point{} at {} to training "
"set.").format(self.S - 1, "" + "s" * (self.S > 2),
self.mus), 2)
self.samplingEngine.iterSample(self.mus)
self._S = len(self.mus)
self._approxParameters["S"] = self.S
self.muTest = emptyParameterList()
self.muTest.reset((len(muTestBase) + 1, self.mus.shape[1]))
self.muTest.data[: -1] = muTestBase.data
self.muTest.data[-1] = muLast.data
def setupApprox(self, plotEst : bool = False):
"""Compute rational interpolant."""
if self.checkComputedApprox():
return True
RROMPyAssert(self._mode, message = "Cannot setup approximant.")
vbMng(self, "INIT", "Setting up {}.". format(self.name()), 5)
self.musMarginal = self.samplerMarginal.generatePoints(self.SMarginal)
S0 = copy(self.S)
Qs, Ps = [], []
self.computeScaleFactor()
self._scaleFactorOldPivot = copy(self.scaleFactor)
self.scaleFactor = self.scaleFactorPivot
nparEff = self.npar
self._temporaryPivot = 1
samplingEngs = []
for j in range(len(self.musMarginal)):
self._S = S0
self.musMargLoc = self.musMarginal[j]
RationalInterpolantGreedy.setupSampling(self)
self.trainedModel = None
self.verbosity -= 5
super().setupApprox(plotEst)
self.verbosity += 5
samplingEngs += [copy(self.samplingEngine)]
Qs = Qs + [copy(self.trainedModel.data.Q)]
Ps = Ps + [copy(self.trainedModel.data.P)]
del self.musMargLoc
# other finalization instructions
self.setupSampling()
self.samplingEngine.resetHistory(len(self.musMarginal))
for j in range(len(self.musMarginal)):
self.samplingEngine.setsample(samplingEngs[j].samples, j, False)
self.samplingEngine.mus[j] = copy(samplingEngs[j].mus)
self.samplingEngine.nsamples[j] = samplingEngs[j].nsamples
self.samplingEngine.postprocessuBulk(j)
if j == 0:
self._mus = parameterList(samplingEngs[j].mus, nparEff)
else:
self._mus.append(samplingEngs[j].mus)
if self.POD:
self.samplingEngine.coalesceSamples(self.interpRcondMarginal)
postR = self.samplingEngine.RPODCoalesced
else:
self.samplingEngine.coalesceSamples()
postR = np.eye(self.samplingEngine.samplesCoalesced.shape[1])
# update Ps by post-multiplication with suitable matrix
idxCurr = 0
for j in range(len(self.musMarginal)):
nsj = Ps[j].coeffs.shape[1]
Ps[j].coeffs = dot(Ps[j].coeffs,
postR[:, idxCurr : idxCurr + nsj].T)
idxCurr = idxCurr + nsj
self.scaleFactor = self._scaleFactorOldPivot
del self._scaleFactorOldPivot, self._temporaryPivot
pMat = self.samplingEngine.samplesCoalesced.data
pMatEff = dot(self.HFEngine.C, pMat)
self.trainedModel = self.tModelType()
self.trainedModel.verbosity = self.verbosity
self.trainedModel.timestamp = self.timestamp
datadict = {"mu0": self.mu0, "projMat": pMatEff,
"scaleFactor": self.scaleFactor,
"rescalingExp": self.HFEngine.rescalingExp,
"directionPivot": self.directionPivot}
self.trainedModel.data = self.initializeModelData(datadict)[0]
self.trainedModel.data.mus = copy(self.mus)
self.trainedModel.data.musMarginal = copy(self.musMarginal)
self.trainedModel.data.marginalInterp = self._setupMarginalInterp()
self.trainedModel.data.Qs, self.trainedModel.data.Ps = Qs, Ps
vbMng(self, "INIT", "Matching poles.", 10)
self.trainedModel.initializeFromRational(self.HFEngine,
self.matchingWeight, self.POD,
self.approx_state)
vbMng(self, "DEL", "Done matching poles.", 10)
if not np.isinf(self.cutOffTolerance):
vbMng(self, "INIT", "Recompressing by cut-off.", 10)
msg = self.trainedModel.recompressByCutOff([-1., 1.],
self.cutOffTolerance,
self.cutOffType)
vbMng(self, "DEL", "Done recompressing." + msg, 10)
self.trainedModel.data.approxParameters = copy(self.approxParameters)
vbMng(self, "DEL", "Done setting up approximant.", 5)

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