Add imdb dataset

* update docs

* add imdb dataset

* update codes

PaddleNLP/paddlenlp/datasets/__init__.py

@@ -15,6 +15,7 @@
 from .chnsenticorp import *
 from .dataset import *
 from .glue import *
+from .imdb import *
 from .lcqmc import *
 from .msra_ner import *
 from .peoples_daily_ner import *

PaddleNLP/paddlenlp/datasets/imdb.py

+# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import io
+import os
+import string
+
+import numpy as np
+import paddle
+from paddle.io import Dataset
+
+from paddlenlp.utils.env import DATA_HOME
+from paddlenlp.utils.downloader import get_path_from_url
+
+__all__ = ['Imdb']
+
+
+class Imdb(Dataset):
+    """
+    Implementation of `IMDB <https://www.imdb.com/interfaces/>`_ dataset.
+
+    """
+    URL = 'https://dataset.bj.bcebos.com/imdb%2FaclImdb_v1.tar.gz'
+    MD5 = '7c2ac02c03563afcf9b574c7e56c153a'
+
+    def __init__(
+            self,
+            root=None,
+            mode='train', ):
+        assert mode in [
+            "train", "test"
+        ], "Unknown mode %s, it should be 'train' or 'test'." % mode
+        if root is None:
+            root = DATA_HOME
+        data_dir = os.path.join(root, "aclImdb")
+
+        if not os.path.exists(data_dir):
+            data_dir = get_path_from_url(self.URL, root, self.MD5)
+
+        self.examples = self._read_data_file(data_dir, mode)
+
+    def _read_data_file(self, data_dir, mode):
+        # remove punctuations ad-hoc.
+        translator = str.maketrans('', '', string.punctuation)
+
+        def _load_data(label):
+            root = os.path.join(data_dir, mode, label)
+            data_files = os.listdir(root)
+
+            if label == "pos":
+                label_id = 1
+            elif label == "neg":
+                label_id = 0
+
+            all_samples = []
+            for f in data_files:
+                f = os.path.join(root, f)
+                data = io.open(f, 'r', encoding='utf8').readlines()
+                data = data[0].translate(translator)
+                all_samples.append((data, label_id))
+
+            return all_samples
+
+        data_set = _load_data("pos")
+        data_set.extend(_load_data("neg"))
+        np.random.shuffle(data_set)
+
+        return data_set
+
+    def __getitem__(self, idx):
+        return self.examples[idx]
+
+    def __len__(self):
+        return len(self.examples)
+
+    def get_labels(self):
+        return ["0", "1"]