关于变量输入问题

[lovejing0306]

楼主，您好！我想问下您， x = [pnyn2idx.get(pnyn, 1) for pnyn in pnyn_sent] # 1: OOV y = [hanzi2idx.get(hanzi, 1) for hanzi in hanzi_sent] # 1: OOV

xs.append(np.array(x, np.int32).tostring()) ys.append(np.array(y, np.int32).tostring()) 为什么这里要把x和y转换成字符串类型那？