def get_iou(bboxes1, bboxes2):
    """
    Adapted from https://gist.github.com/zacharybell/8d9b1b25749fe6494511f843361bb167
    Calculates the intersection-over-union of two bounding boxes.
    Args:
        bbox1 (numpy.array, list of floats): bounding box in format x1,y1,x2,y2.
        bbox2 (numpy.array, list of floats): bounding box in format x1,y1,x2,y2.
    Returns:
        int: intersection-over-onion of bbox1, bbox2
    """
    ious = []
    for bbox1, bbox2 in zip(bboxes1, bboxes2):
        bbox1 = [float(x) for x in bbox1]
        bbox2 = [float(x) for x in bbox2]
        (x0_1, y0_1, x1_1, y1_1) = bbox1
        (x0_2, y0_2, x1_2, y1_2) = bbox2
        # get the overlap rectangle
        overlap_x0 = max(x0_1, x0_2)
        overlap_y0 = max(y0_1, y0_2)
        overlap_x1 = min(x1_1, x1_2)
        overlap_y1 = min(y1_1, y1_2)
        # check if there is an overlap
        if overlap_x1 - overlap_x0 <= 0 or overlap_y1 - overlap_y0 <= 0:
            ious.append(0)
            continue
        # if yes, calculate the ratio of the overlap to each ROI size and the unified size
        size_1 = (x1_1 - x0_1) * (y1_1 - y0_1)
        size_2 = (x1_2 - x0_2) * (y1_2 - y0_2)
        size_intersection = (overlap_x1 - overlap_x0) * (overlap_y1 - overlap_y0)
        size_union = size_1 + size_2 - size_intersection
        iou = size_intersection / size_union
        ious.append(iou)
    return ious