def prediction_string(predicted_boxes, confidences):
    """
    :param predicted_boxes: [[x1, y1, w1, h1], [x2, y2, w2, h2], ...] list of predicted boxes coordinates
    :param confidences: [c1, c2, ...] list of confidence values for the predicted boxes
    :returns: prediction string 'c1 x1 y1 w1 h1 c2 x2 y2 w2 h2 ...'
    """
    prediction_string = ""
    for c, box in zip(confidences, predicted_boxes):
        prediction_string += (
            " " + str(c) + " " + " ".join([str(b) for b in box])
        )
    return prediction_string[1:]