Linear interpolation of a 2D line with SciPy.

2d_linear_interpolator.py

from numpy import arange, array, concatenate, cumsum, ediff1d, float64, hypot
from numpy.typing import NDArray
from scipy.interpolate import interp1d


def linear_interpolation(
    x: NDArray[float64],
    y: NDArray[float64],
    linear_displacement: float
) -> tuple[NDArray[float64], NDArray[float64]]:
    """
    Summary
    -------
    interpolate a line with a desired linear displacement between each point

    Parameters
    ----------
    x (NDArray[float64]): x-coordinates of the coarse line [m]
    y (NDArray[float64]): y-coordinates of the coarse line [m]
    linear_displacement (float): desired linear displacement between each point [m]

    Returns
    -------
    interpolated_x (NDArray[float64]): x-coordinates of the interpolated line [m]
    interpolated_y (NDArray[float64]): y-coordinates of the interpolated line [m]
    """
    distance = concatenate(([0], cumsum(hypot(ediff1d(x), ediff1d(y)))))
    points = array([x, y]).T
    interp = interp1d(distance, points, axis=0, kind='linear')
    s = arange(0, distance[-1], linear_displacement)

    return interp(s).T # type: ignore