Function intersections_to_cells

src/table.py:1354–1413

Given a list of points (`intersections`), return all rectangular "cells" that those points describe. `intersections` should be a dictionary with (x0, top) tuples as keys, and a list of edge objects as values. The edge objects should correspond to the edges that touch the inters

(intersections)

def intersections_to_cells(intersections):
    """
    Given a list of points (`intersections`), return all rectangular "cells"
    that those points describe.

    `intersections` should be a dictionary with (x0, top) tuples as keys,
    and a list of edge objects as values. The edge objects should correspond
    to the edges that touch the intersection.
    """

    def edge_connects(p1, p2) -> bool:
        def edges_to_set(edges):
            return set(map(obj_to_bbox, edges))

        if p1[0] == p2[0]:
            common = edges_to_set(intersections[p1]["v"]).intersection(
                edges_to_set(intersections[p2]["v"])
            )
            if len(common):
                return True

        if p1[1] == p2[1]:
            common = edges_to_set(intersections[p1]["h"]).intersection(
                edges_to_set(intersections[p2]["h"])
            )
            if len(common):
                return True
        return False

    points = list(sorted(intersections.keys()))
    n_points = len(points)

    def find_smallest_cell(points, i: int):
        if i == n_points - 1:
            return None
        pt = points[i]
        rest = points[i + 1 :]
        # Get all the points directly below and directly right
        below = [x for x in rest if x[0] == pt[0]]
        right = [x for x in rest if x[1] == pt[1]]
        for below_pt in below:
            if not edge_connects(pt, below_pt):
                continue

            for right_pt in right:
                if not edge_connects(pt, right_pt):
                    continue

                bottom_right = (right_pt[0], below_pt[1])

                if (
                    (bottom_right in intersections)
                    and edge_connects(bottom_right, right_pt)
                    and edge_connects(bottom_right, below_pt)
                ):
                    return (pt[0], pt[1], bottom_right[0], bottom_right[1])
        return None