[Dataset] Add TUDataset (#473)

* add graph classification dataset

* add node label

* add TUDataset

* Modify to consistent with Qi Huang's implementation

* add docs

* Add docs

* Fix change of environment variable

* Update tu.py

* Update tu.py

* Fix error when add node with np.int64

docs/source/api/python/data.rst

@@ -33,6 +33,14 @@ Mini graph classification dataset
 .. autoclass:: MiniGCDataset
     :members: __getitem__, __len__, num_classes
 
+Graph kernel dataset
+````````````````````
+
+For more information about the dataset, see `Benchmark Data Sets for Graph Kernels <https://ls11-www.cs.tu-dortmund.de/staff/morris/graphkerneldatasets>`__.
+
+.. autoclass:: TUDataset
+    :members: __getitem__, __len__
+
 Protein-Protein Interaction dataset
 ```````````````````````````````````
 

docs/source/conf.py

@@ -215,7 +215,8 @@ sphinx_gallery_conf = {
 }
 
 # Compatibility for different backend when builds tutorials
-if os.environ['DGLBACKEND'] == 'mxnet':
+dglbackend = os.environ.get("DGLBACKEND", "")
+if dglbackend == 'mxnet':
     sphinx_gallery_conf['filename_pattern'] = "/*(?<=mx)\.py"
-if os.environ['DGLBACKEND'] == 'pytorch':
+if dglbackend == 'pytorch':
     sphinx_gallery_conf['filename_pattern'] = "/*(?<!mx)\.py"

python/dgl/data/__init__.py

@@ -9,6 +9,7 @@ from .utils import *
 from .sbm import SBMMixture
 from .reddit import RedditDataset
 from .ppi import PPIDataset
+from .tu import TUDataset
 
 def register_data_args(parser):
     parser.add_argument("--dataset", type=str, required=False,

python/dgl/data/tu.py

+from __future__ import absolute_import
+import numpy as np
+import dgl
+import os
+
+from dgl.data.utils import download, extract_archive, get_download_dir
+
+
+class TUDataset(object):
+    """
+    TUDataset contains lots of graph kernel datasets for graph classification.
+    Use provided node feature by default. If no feature provided, use one-hot node label instead.
+    If neither labels provided, use constant for node feature.
+
+    :param name: Dataset Name, such as `ENZYMES`, `DD`, `COLLAB`
+    :param use_pandas: Default: False.
+        Numpy's file read function has performance issue when file is large,
+        using pandas can be faster.
+    :param hidden_size: Default 10. Some dataset doesn't contain features.
+        Use constant node features initialization instead, with hidden size as `hidden_size`.
+
+    """
+
+    _url = r"https://ls11-www.cs.uni-dortmund.de/people/morris/graphkerneldatasets/{}.zip"
+
+    def __init__(self, name, use_pandas=False, hidden_size=10):
+
+        self.name = name
+        self.hidden_size = hidden_size
+        self.extract_dir = self._download()
+
+        if use_pandas:
+            import pandas as pd
+            DS_edge_list = self._idx_from_zero(
+                pd.read_csv(self._file_path("A"), delimiter=",", dtype=int).values)
+        else:
+            DS_edge_list = self._idx_from_zero(
+                np.genfromtxt(self._file_path("A"), delimiter=",", dtype=int))
+
+        DS_indicator = self._idx_from_zero(
+            np.genfromtxt(self._file_path("graph_indicator"), dtype=int))
+        DS_graph_labels = self._idx_from_zero(
+            np.genfromtxt(self._file_path("graph_labels"), dtype=int))
+
+        g = dgl.DGLGraph()
+        g.add_nodes(int(DS_edge_list.max()) + 1)
+        g.add_edges(DS_edge_list[:, 0], DS_edge_list[:, 1])
+        g.add_edges(DS_edge_list[:, 1], DS_edge_list[:, 0])
+
+        node_idx_list = []
+        for idx in range(np.max(DS_indicator) + 1):
+            node_idx = np.where(DS_indicator == idx)
+            node_idx_list.append(node_idx[0])
+        self.graph_lists = g.subgraphs(node_idx_list)
+        self.graph_labels = DS_graph_labels
+
+        try:
+            DS_node_labels = self._idx_from_zero(
+                np.loadtxt(self._file_path("node_labels"), dtype=int))
+            g.ndata['node_label'] = DS_node_labels
+            one_hot_node_labels = self._to_onehot(DS_node_labels)
+            for idxs, g in zip(node_idx_list, self.graph_lists):
+                g.ndata['feat'] = one_hot_node_labels[idxs, :]
+        except IOError:
+            print("No Node Label Data")
+
+        try:
+            DS_node_attr = np.loadtxt(self._file_path("node_attributes"), delimiter=",")
+            for idxs, g in zip(node_idx_list, self.graph_lists):
+                g.ndata['feat'] = DS_node_attr[idxs, :]
+        except IOError:
+            print("No Node Attribute Data")
+
+        if 'feat' not in g.ndata.keys():
+            for idxs, g in zip(node_idx_list, self.graph_lists):
+                g.ndata['feat'] = np.ones((g.number_of_nodes(), hidden_size))
+            print("Use Constant one as Feature with hidden size {}".format(hidden_size))
+
+    def __getitem__(self, idx):
+        """Get the i^th sample.
+        Paramters
+        ---------
+        idx : int
+            The sample index.
+        Returns
+        -------
+        (dgl.DGLGraph, int)
+            DGLGraph with node feature stored in `feat` field and node label in `node_label` if available.
+            And its label.
+        """
+        g = self.graph_lists[idx]
+        return g, self.graph_labels[idx]
+
+    def __len__(self):
+        return len(self.graph_lists)
+
+    def _download(self):
+        download_dir = get_download_dir()
+        zip_file_path = os.path.join(download_dir, "tu_{}.zip".format(self.name))
+        download(self._url.format(self.name), path=zip_file_path)
+        extract_dir = os.path.join(download_dir, "tu_{}".format(self.name))
+        extract_archive(zip_file_path, extract_dir)
+        return extract_dir
+
+    def _file_path(self, category):
+        return os.path.join(self.extract_dir, self.name, "{}_{}.txt".format(self.name, category))
+
+    @staticmethod
+    def _idx_from_zero(idx_tensor):
+        return idx_tensor - np.min(idx_tensor)
+
+    @staticmethod
+    def _to_onehot(label_tensor):
+        label_num = label_tensor.shape[0]
+        assert np.min(label_tensor) == 0
+        one_hot_tensor = np.zeros((label_num, np.max(label_tensor) + 1))
+        one_hot_tensor[np.arange(label_num), label_tensor] = 1
+        return one_hot_tensor
+
+    def statistics(self):
+        return self.graph_lists[0].ndata['feat'].shape[1]
+