Runtime Train/Test dataset split questions

[YiKangOY]

Hi! I have some graphs and I want to put some of them into training set and some into test set at runtime.
Now I create two datasets, one for training and one for testing.
train_dataset = MyOwnDataset('dataset_train')
test_dataset = MyOwnDataset('dataset_test')
But these requires building dataset everytime I change the train and test split.
Is there any way to put all graphs into one dataset and obtain training set and test set at runtime?

P.S. train_dataset= dataset[0:10] + dataset[20:30] is not a good choice because this will make train_dataset a ConcatDataset object and can not directly access the properties of Pyg datasets like dataset.x