gemseo.problems.dataset.rosenbrock — GEMSEO 4.0.0 documentation

# Copyright 2021 IRT Saint Exupéry, https://www.irt-saintexupery.com
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#    INITIAL AUTHORS - initial API and implementation and/or initial
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#        :author: Matthias De Lozzo
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"""
Rosenbrock dataset
==================

This :class:`.Dataset` contains 100 evaluations
of the well-known Rosenbrock function:

.. math::

   f(x,y)=(1-x)^2+100(y-x^2)^2

This function is known for its global minimum at point (1,1),
its banana valley and the difficulty to reach its minimum.

This :class:`.Dataset` is based on a full-factorial
design of experiments.

`More information about the Rosenbrock function
<https://en.wikipedia.org/wiki/Rosenbrock_function>`_
"""
from __future__ import annotations

from numpy import hstack
from numpy import linspace
from numpy import meshgrid

from gemseo.core.dataset import Dataset


[docs]class RosenbrockDataset(Dataset):
    """Rosenbrock dataset parametrization."""

    def __init__(
        self,
        name: str = "Rosenbrock",
        by_group: bool = True,
        n_samples: int = 100,
        categorize: bool = True,
        opt_naming: bool = True,
    ) -> None:
        """
        Args:
            name: The name of the dataset.
            by_group: Whether to store the data by group.
                Otherwise, store them by variables.
            n_samples: The number of samples.
            categorize: Whether to distinguish
                between the different groups of variables.
            opt_naming: Whether to use an optimization naming.
        """
        super().__init__(name, by_group)
        root_n_samples = int(n_samples**0.5)
        x_i = linspace(-2.0, 2.0, root_n_samples)
        x_i, y_i = meshgrid(x_i, x_i)
        x_i = x_i.reshape((-1, 1))
        y_i = y_i.reshape((-1, 1))
        z_i = 100 * (y_i - x_i**2) ** 2 + (1 - x_i) ** 2
        data = hstack((x_i, y_i, z_i))
        if categorize:
            if opt_naming:
                groups = {"x": Dataset.DESIGN_GROUP, "rosen": Dataset.FUNCTION_GROUP}
            else:
                groups = {"x": Dataset.INPUT_GROUP, "rosen": Dataset.OUTPUT_GROUP}
        else:
            groups = None
        self.set_from_array(data, ["x", "rosen"], {"x": 2, "rosen": 1}, groups=groups)
        self.set_metadata("root_n_samples", root_n_samples)
Source code for gemseo.problems.dataset.rosenbrock
