使用Python学习深度学习，我无法理解下面的简单代码，这些代码将整数序列编码为二进制矩阵。
def vectorize_sequences(sequences, dimension=10000):
# Create an all-zero matrix of shape (len(sequences), dimension)
results = np.zeros((len(sequences), dimension))
for i, sequence in enumerate(sequences):
results[i, sequence] = 1. # set specific indices of results[i] to 1s
return results
(train_data, train_labels), (test_data, test_labels) = imdb.load_data(num_words=10000)
x_train = vectorize_sequences(train_data)
x_train的输出类似于
x_train [0]数组（[0.，1.，1。，...，0.，0.，0。]）
有人可以0.在x_train数组中稍微介绍一下的存在，而1.在每次下i一次迭代中仅追加时吗？我的意思是不应该全1吗？