def polygon_to_cells()

in src/h3/_cy/latlng.pyx [0:0]

• 16 lines of code
• 2 McCabe index (conditional complexity)

def polygon_to_cells(outer, int res, holes=None):
    """ Get the set of cells whose center is contained in a polygon.

    The polygon is defined similarity to the GeoJson standard, with an exterior
    `outer` ring of lat/lng points, and a list of `holes`, each of which are also
    rings of lat/lng points.

    Each ring may be in clockwise or counter-clockwise order
    (right-hand rule or not), and may or may not be a closed loop (where the last
    element is equal to the first).
    The GeoJSON spec requires the right-hand rule and a closed loop, but
    this function relaxes those constraints.

    Unlike the GeoJson standard, the elements of the lat/lng pairs of each
    ring are in lat/lng order, instead of lng/lat order.

    We'll handle translation to different formats in the Python code,
    rather than the Cython code.

    Parameters
    ----------
    outer : list or tuple
        A ring given by a sequence of lat/lng pairs.
    res : int
        The resolution of the output hexagons
    holes : list or tuple
        A collection of rings, each given by a sequence of lat/lng pairs.
        These describe any the "holes" in the polygon.
    """
    cdef:
        uint64_t n

    check_res(res)

    if not outer:
        return H3MemoryManager(0).to_mv()

    gp = GeoPolygon(outer, holes=holes)

    check_for_error(
        h3lib.maxPolygonToCellsSize(&gp.gp, res, 0, &n)
    )

    hmm = H3MemoryManager(n)
    check_for_error(
        h3lib.polygonToCells(&gp.gp, res, 0, hmm.ptr)
    )
    mv = hmm.to_mv()

    return mv