Benchmark the NLOscillator test function

import openturns as ot
import otbenchmark as otb
import openturns.viewer as otv

problem = otb.NLOscillatorSensitivity()
print(problem)

name = N.L. Oscillator
distribution = ComposedDistribution(class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=21.5 sigma=2.15 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=3.06308 sigmaLog=0.0997513 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=1.5 sigma=0.15 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=0.40049 sigmaLog=0.0997513 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=0.01 sigma=0.001 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=-4.61015 sigmaLog=0.0997513 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=1 sigma=0.2 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=-0.0196104 sigmaLog=0.198042 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=0.01 sigma=0.002 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=-4.62478 sigmaLog=0.198042 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=0.05 sigma=0.02 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=-3.06994 sigmaLog=0.385253 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=0.02 sigma=0.01 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=-4.02359 sigmaLog=0.472381 gamma=0, class=ParametrizedDistribution parameters=class=LogNormalMuSigma name=Unnamed mu=100 sigma=10 gamma=0 distribution=class=LogNormal name=LogNormal dimension=1 muLog=4.6002 sigmaLog=0.0997513 gamma=0, IndependentCopula(dimension = 8))
function = class=PythonEvaluation name=OpenTURNSPythonFunction
firstOrderIndices = [0.4,0.03,0.09,0.18,0.12,0.05,0.05,0]
totalOrderIndices = [0.4,0.04,0.1,0.23,0.16,0.07,0.06,0.01]

distribution = problem.getInputDistribution()
model = problem.getFunction()

Exact first and total order

exact_first_order = problem.getFirstOrderIndices()
exact_first_order

class=Point name=Unnamed dimension=8 values=[0.4,0.03,0.09,0.18,0.12,0.05,0.05,0]

exact_total_order = problem.getTotalOrderIndices()
exact_total_order

class=Point name=Unnamed dimension=8 values=[0.4,0.04,0.1,0.23,0.16,0.07,0.06,0.01]

Plot the function

Create X/Y data

ot.RandomGenerator.SetSeed(0)
size = 200
inputDesign = ot.MonteCarloExperiment(distribution, size).generate()
outputDesign = model(inputDesign)

dimension = distribution.getDimension()
full_sample = ot.Sample(size, 1 + dimension)
full_sample[:, range(dimension)] = inputDesign
full_sample[:, dimension] = outputDesign
full_description = list(inputDesign.getDescription())
full_description.append(outputDesign.getDescription()[0])
full_sample.setDescription(full_description)

marginal_distribution = ot.ComposedDistribution(
    [
        ot.KernelSmoothing().build(full_sample.getMarginal(i))
        for i in range(1 + dimension)
    ]
)
clouds = ot.VisualTest.DrawPairsMarginals(full_sample, marginal_distribution)
_ = otv.View(clouds, figure_kw={"figsize": (10.0, 10.0)})

output_distribution = ot.KernelSmoothing().build(outputDesign)
_ = otv.View(output_distribution.drawPDF())

Perform sensitivity analysis

Create X/Y data

ot.RandomGenerator.SetSeed(0)
size = 10000
inputDesign = ot.SobolIndicesExperiment(distribution, size).generate()
outputDesign = model(inputDesign)

Compute first order indices using the Saltelli estimator

sensitivityAnalysis = ot.SaltelliSensitivityAlgorithm(inputDesign, outputDesign, size)
computed_first_order = sensitivityAnalysis.getFirstOrderIndices()
computed_total_order = sensitivityAnalysis.getTotalOrderIndices()

Compare with exact results

print("Sample size : ", size)
# First order
# Compute absolute error (the LRE cannot be computed,
# because S can be zero)
print("Computed first order = ", computed_first_order)
print("Exact first order = ", exact_first_order)
# Total order
print("Computed total order = ", computed_total_order)
print("Exact total order = ", exact_total_order)

Sample size :  10000
Computed first order =  [0.374552,0.0347919,0.0853174,0.186246,0.120437,0.04356,0.0358369,0.00467826]
Exact first order =  [0.4,0.03,0.09,0.18,0.12,0.05,0.05,0]
Computed total order =  [0.375092,0.0778412,0.127126,0.279952,0.201389,0.0667096,0.0458004,0.00812321]
Exact total order =  [0.4,0.04,0.1,0.23,0.16,0.07,0.06,0.01]

_ = otv.View(sensitivityAnalysis.draw())

otv.View.ShowAll()