[Dataset] QM7bDataset (#1915)

* PPIDataset

* Revert "PPIDataset"

This reverts commit 264bd0c960cfa698a7bb946dad132bf52c2d0c8a.

* QM7bDataset

* Update qm7b.py
Co-authored-by: xiang song(charlie.song) <classicxsong@gmail.com>

python/dgl/data/__init__.py

@@ -16,7 +16,7 @@ from .gindt import GINDataset
 from .bitcoinotc import BitcoinOTC
 from .gdelt import GDELT
 from .icews18 import ICEWS18
-from .qm7b import QM7b
+from .qm7b import QM7b, QM7bDataset
 from .dgl_dataset import DGLDataset, DGLBuiltinDataset
 from .citation_graph import CoraGraphDataset, CiteseerGraphDataset, PubmedGraphDataset
 

python/dgl/data/qm7b.py

+"""QM7b dataset for graph property prediction (regression)."""
 from scipy import io
 import numpy as np
 import os
 
-from .utils import get_download_dir, download
-from ..utils import retry_method_with_fix
-from .. import convert
+from .dgl_dataset import DGLDataset
+from .utils import download, save_graphs, load_graphs, \
+    check_sha1, deprecate_property
+from .. import backend as F
+from ..convert import graph as dgl_graph
+
+
+class QM7bDataset(DGLDataset):
+    r"""QM7b dataset for graph property prediction (regression)
 
-class QM7b(object):
-    """
     This dataset consists of 7,211 molecules with 14 regression targets.
-    Nodes means atoms and edges means bonds. Edge data 'h' means 
+    Nodes means atoms and edges means bonds. Edge data 'h' means
     the entry of Coulomb matrix.
+    Reference: http://quantum-machine.org/datasets/
+
+    Statistics
+    ----------
+    Number of graphs: 7,211
+    Number of regression targets: 14
+    Average number of nodes: 15
+    Average number of edges: 245
+    Edge feature size: 1
+
+    Parameters
+    ----------
+    raw_dir : str
+        Raw file directory to download/contains the input data directory.
+        Default: ~/.dgl/
+    force_reload : bool
+        Whether to reload the dataset. Default: False
+    verbose: bool
+        Whether to print out progress information. Default: True.
 
-    Reference:
-    - `QM7b Dataset <http://quantum-machine.org/datasets/>`_
+    Attributes
+    ----------
+    num_labels : int
+        Number of labels for each graph, i.e. number of prediction tasks
 
+    Raises
+    ------
+    UserWarning
+        If the raw data is changed in the remote server by the author.
+
+    Examples
+    --------
+    >>> data = QM7bDataset()
+    >>> data.num_labels
+    14
+    >>>
+    >>> # iterate over the dataset
+    >>> for g, label in data:
+    ...     edge_feat = g.edata['h']  # get edge feature
+    ...     # your code here...
+    ...
+    >>>
     """
+
     _url = 'http://deepchem.io.s3-website-us-west-1.amazonaws.com/' \
-        'datasets/qm7b.mat'
+           'datasets/qm7b.mat'
+    _sha1_str = '4102c744bb9d6fd7b40ac67a300e49cd87e28392'
 
-    def __init__(self):
-        self.dir = get_download_dir()
-        self.path = os.path.join(self.dir, 'qm7b', "qm7b.mat")
-        self.graphs = []
-        self._load(self.path)
+    def __init__(self, raw_dir=None, force_reload=False, verbose=False):
+        super(QM7bDataset, self).__init__(name='qm7b',
+                                          url=self._url,
+                                          raw_dir=raw_dir,
+                                          force_reload=force_reload,
+                                          verbose=verbose)
 
-    def _download(self):
-        download(self._url, path=self.path)
+    def process(self):
+        mat_path = self.raw_path + '.mat'
+        if not check_sha1(mat_path, self._sha1_str):
+            raise UserWarning('File {} is downloaded but the content hash does not match.'
+                              'The repo may be outdated or download may be incomplete. '
+                              'Otherwise you can create an issue for it.'.format(self.name))
+        self.graphs, self.label = self._load_graph(mat_path)
 
-    @retry_method_with_fix(_download)
-    def _load(self, filename):
-        data = io.loadmat(self.path)
-        labels = data['T']
+    def _load_graph(self, filename):
+        data = io.loadmat(filename)
+        labels = F.tensor(data['T'], dtype=F.data_type_dict['float32'])
         feats = data['X']
         num_graphs = labels.shape[0]
-        self.label = labels
+        graphs = []
         for i in range(num_graphs):
             edge_list = feats[i].nonzero()
-            g = convert.graph(edge_list)
-            g.edata['h'] = feats[i][edge_list[0], edge_list[1]].reshape(-1, 1)
-            self.graphs.append(g)
-        
+            g = dgl_graph(edge_list)
+            g.edata['h'] = F.tensor(feats[i][edge_list[0], edge_list[1]].reshape(-1, 1),
+                                    dtype=F.data_type_dict['float32'])
+            graphs.append(g)
+        return graphs, labels
+
+    def save(self):
+        """save the graph list and the labels"""
+        graph_path = os.path.join(self.save_path, 'dgl_graph.bin')
+        save_graphs(str(graph_path), self.graphs, {'labels': self.label})
+
+    def has_cache(self):
+        graph_path = os.path.join(self.save_path, 'dgl_graph.bin')
+        return os.path.exists(graph_path)
+
+    def load(self):
+        graphs, label_dict = load_graphs(os.path.join(self.save_path, 'dgl_graph.bin'))
+        self.graphs = graphs
+        self.label = label_dict['labels']
+
+    def download(self):
+        file_path = os.path.join(self.raw_dir, self.name + '.mat')
+        download(self.url, path=file_path)
+
+    @property
+    def num_labels(self):
+        """Number of labels for each graph, i.e. number of prediction tasks."""
+        return 14
+
     def __getitem__(self, idx):
+        r""" Get graph and label by index
+
+        Parameters
+        ----------
+        idx : int
+            Item index
+
+        Returns
+        -------
+        (dgl.DGLGraph, Tensor)
+        """
         return self.graphs[idx], self.label[idx]
-    
+
     def __len__(self):
+        r"""Number of graphs in the dataset"""
         return len(self.graphs)
+
+
+QM7b = QM7bDataset