错误'file'对象没有属性'__getitem __'

Question

尝试执行以下代码时出现TypeError 'file' object has no attribute '__getitem__'错误。该行的错误是：

  

表示x，y表示zip（train_set [0]，train_set [1]）：

代码在这里：

def load_data(maxlen=None, sort_by_len=True):

    train_set = open('./ptb.train.txt', 'r')
    train_set.close()

    if maxlen:
        new_train_set_x = []
        new_train_set_y = []
        for x, y in zip(train_set[0], train_set[1]):
            if len(x) < maxlen:
                new_train_set_x.append(x)
                new_train_set_y.append(y)
        train_set = (new_train_set_x, new_train_set_y)
        del new_train_set_x, new_train_set_y

    train_set_x, train_set_y = train_set

    def len_argsort(seq):
            return sorted(range(len(seq)), key=lambda x: len(seq[x]))

    if sort_by_len:

        sorted_index = len_argsort(train_set_x)
        train_set_x = [train_set_x[i] for i in sorted_index]
        train_set_y = [train_set_y[i] for i in sorted_index]

    train = (train_set_x, train_set_y)

    return train

对于如何解决此问题，我将不胜感激！谢谢！