Source code for data_morph.shapes.points.heart

"""Heart shape."""

import numpy as np

from ...data.dataset import Dataset
from ..bases.point_collection import PointCollection




class Heart(PointCollection):
    """
    Class for the heart shape.

    .. plot::
       :scale: 75
       :caption:
            This shape is generated using the panda dataset.

        from data_morph.data.loader import DataLoader
        from data_morph.plotting.diagnostics import plot_shape_on_dataset
        from data_morph.shapes.points import Heart

        dataset = DataLoader.load_dataset('panda')
        shape = Heart(dataset)
        plot_shape_on_dataset(dataset, shape, show_bounds=False, alpha=0.25)

    Parameters
    ----------
    dataset : Dataset
        The starting dataset to morph into other shapes.

    Notes
    -----
    The formula for the heart shape is inspired by
    `Heart Curve <https://mathworld.wolfram.com/HeartCurve.html>`_:

        Weisstein, Eric W. "Heart Curve." From `MathWorld <https://mathworld.wolfram.com/>`_
        --A Wolfram Web Resource. https://mathworld.wolfram.com/HeartCurve.html
    """

    def __init__(self, dataset: Dataset) -> None:
        data_bounds = dataset.data_bounds
        (_, xmax), (_, ymax) = data_bounds
        x_shift, y_shift = data_bounds.center

        t = np.linspace(-3, 3, num=80)

        x = 16 * np.sin(t) ** 3
        y = 13 * np.cos(t) - 5 * np.cos(2 * t) - 2 * np.cos(3 * t) - np.cos(4 * t)

        # scale by the half the widest width of the heart
        scale_factor = min((xmax - x_shift), (ymax - y_shift)) / 16

        super().__init__(
            *self._center(
                np.stack([x * scale_factor, y * scale_factor], axis=1), data_bounds
            )
        )