#! /usr/bin/env python

import openturns as ot
import openturns.testing as ott

ot.TESTPREAMBLE()


def fitKriging(covarianceModel):
    """
    Fit the parameters of a kriging metamodel.
    """
    coordinates = ot.Sample(
        [
            [1.0, 1.0],
            [5.0, 1.0],
            [9.0, 1.0],
            [1.0, 3.5],
            [5.0, 3.5],
            [9.0, 3.5],
            [1.0, 6.0],
            [5.0, 6.0],
            [9.0, 6.0],
        ]
    )
    observations = ot.Sample(
        [[25.0], [25.0], [10.0], [20.0], [25.0], [20.0], [15.0], [25.0], [25.0]]
    )
    basis = ot.ConstantBasisFactory(2).build()
    algo = ot.KrigingAlgorithm(coordinates, observations, covarianceModel, basis)
    algo.run()
    krigingResult = algo.getResult()
    return krigingResult


# Isotropic covariance model
myIsotropicKernel = ot.IsotropicCovarianceModel(ot.SquaredExponential(), 2)
krigingFittedCovarianceModel = fitKriging(myIsotropicKernel).getCovarianceModel()
ott.assert_almost_equal(krigingFittedCovarianceModel.getScale()[0], 2.86427, 0.0, 1e-4)
ott.assert_almost_equal(
    krigingFittedCovarianceModel.getAmplitude()[0], 6.65231, 0.0, 1e-4
)
