from typing import Sequence
import numpy as np


def get_anchor_grid(
    num_rows: int,
    num_cols: int,
    scale_factor: float,
    anchor_widths: Sequence[float],
    aspect_ratios: Sequence[float],
) -> np.ndarray:
    anchor_grid = np.empty(
        [len(width), len(ratio), num_rows, num_cols, 4], dtype=int)
    for width_idx, width in enumerate(anchor_widths):
        for ratio_idx, ratio in enumerate(aspect_ratios):
            for row in range(num_rows):
                for col in range(num_cols):
                    anchor_point = (
                        col * scale_factor + scale_factor/2, row * scale_factor + scale_factor / 2)
                    anchor_grid[width_idx, ratio_idx, row, col] = get_box(
                        width, ratio, anchor_point)

    return anchor_grid


def get_box(width: float, ratio: float, anchor_point: tuple[float, float]) -> np.ndarray:
    box = np.empty(4)
    box[0] = anchor_point[0] - (width / 2)
    box[1] = anchor_point[1] - (width * ratio / 2)
    box[2] = anchor_point[0] + (width / 2)
    box[3] = anchor_point[1] + (width * ratio / 2)
    return box