import openturns as ot
from openturns.viewer import View

f = ot.SymbolicFunction(['x'],  ['x * sin(x)'])
sampleX = [[1.0], [2.0], [3.0], [4.0], [5.0], [6.0], [7.0], [8.0]]
sampleY = f(sampleX)
basis = ot.Basis([ot.SymbolicFunction(['x'], ['x']),
                  ot.SymbolicFunction(['x'], ['x^2'])])
covarianceModel = ot.SquaredExponential([1.0])
covarianceModel.setActiveParameter([])
algo = ot.KrigingAlgorithm(sampleX, sampleY, covarianceModel, basis)
algo.run()
result = algo.getResult()

graph = f.draw(0.0, 10.0)
graph.add(result.getMetaModel().draw(0.0, 10.0))
graph.add(ot.Cloud(sampleX, sampleY))
graph.setColors(['blue', 'red', 'black'])
graph.setLegends(['model', 'meta model', 'sample'])
graph.setLegendPosition('topleft')
graph.setTitle('y(x)=x * sin(x)')
View(graph, figure_kwargs={'figsize': (8, 4)})
