def prepare_data(seqs,labels):
	"""
	create the matrics from the datasets
	this pad each sequence to the same length:the length of the longest seuence or maxlen.
	if maxlen is set,we will out all sequence to this maximum length.
	this swap the axis
	"""
	#x:a list of sentences

	lengths = [len(s) for s in seqs]
	n_samples = len(seqs)
	maxlen = numpy.max(lengths)

	x = numpy.zeros((maxlen,n_samples)).astype('int64')
	x_mask = numpy.ones((maxlen,n_samples)).astype(theano.config.floatx)

	for idx,s in enumerate(seqs):
		x[:lengths[idx],idx] = s

	x_mask *= (1-(x == 0))  #构建mask矩阵的绝佳技巧

	return x,x_mask,labels