Source code for MLV_toolbox.getDistanceFromLineSegment

from .VecLD import VecLD
import numpy as np

def getDistanceFromLineSegment(XY: np.ndarray) -> np.ndarray:
    """
    Computes the distance between a set of points and a line segment in 2D space.

    Args:
        XY: A NumPy array of shape (N, 4) containing the coordinates of N line segments.
            Each row of the array should contain the x and y coordinates of the starting
            and ending points of a line segment, in that order.

    Returns:
        A NumPy array of shape (N,) containing the distances between each line segment
        and the set of points.

    Raises:
        ValueError: If the input array is not of shape (N, 4).
    """
    
    if XY.shape[0] <= 2:
        d = 0
    else:
        x1 = XY[0, 0]
        y1 = XY[0, 1]
        x2 = XY[-1, 0] # -1 is the last coordinate
        y2 = XY[-1, 1] # -1 is the last coordinate
        mx = x1 - x2
        my = y1 - y2
        
        a = 1
        n = XY.shape[0]
        total_d = 0
        
        if my != 0:
            b = -mx/my
            c = -(x1+b*y1)

            for i in range(1, n-1):
                x0 = XY[i, 0]
                y0 = XY[i, 1]
                d = abs(a*x0+b*y0+c)/np.sqrt(a*a+b*b)
                total_d = total_d + d
        else:
            for i in range(1, n-1):
                y0 = XY[i, 1]
                total_d = total_d + abs(y0-y1)
        d = total_d/(n-2)

    return d
    
setattr(VecLD, 'getDistanceFromLineSegment', getDistanceFromLineSegment)