def __init__(self, root, train=True, download=False, min_rating=0.0):
        """
        Args:
            root (string): Root directory of dataset where
                ``MovieLens/processed/training.pt``
                and  ``MovieLens/processed/test.pt`` exist.
            train (bool, optional): If True, creates dataset from
                ``training.pt``, otherwise from ``test.pt``.
            download (bool, optional): If true, downloads the dataset from
                the internet and puts it in root directory. If dataset
                is already downloaded, it is not downloaded again.
            min_rating (float, optional): Minimum rating to include in
                the interaction matrix

        Raises:
            RuntimeError: If ``download is False`` and the dataset not found.
        """
        if isinstance(root, torch._six.string_classes):
            root = os.path.expanduser(root)

        self.root = root
        self.train = train
        self.min_rating = min_rating

        if download:
            self._download()

        self._fetch_movies()

        if not self._check_exists():
            raise RuntimeError("Dataset not found. Set `download=True`")

        if self.train:
            data_file = self.training_file
        else:
            data_file = self.test_file

        self.data = torch.load(os.path.join(self.processed_folder, data_file))

        Args:
            root (string): Root directory of dataset where
                ``MovieLens/processed/training.pt``
                and  ``MovieLens/processed/test.pt`` exist.
            train (bool, optional): If True, creates dataset from
                ``training.pt``, otherwise from ``test.pt``.
            download (bool, optional): If true, downloads the dataset from
                the internet and puts it in root directory. If dataset
                is already downloaded, it is not downloaded again.
            min_rating (float, optional): Minimum rating to include in
                the interaction matrix

        Raises:
            RuntimeError: If ``download is False`` and the dataset not found.
        
catalyst/contrib/datasets/movielens.py