FEA: Add dynamic negative sampling

docs/source/user_guide/config/training_settings.rst

@@ -9,10 +9,11 @@ Training settings are designed to set parameters about model training.
   Range in ``['adam', 'sgd', 'adagrad', 'rmsprop', 'sparse_adam']``.
 - ``learning_rate (float)`` : Learning rate. Defaults to ``0.001``.
 - ``neg_sampling(dict)``: This parameter controls the negative sampling for model training.
-  The key range is ``['uniform', 'popularity']``, which decides the distribution of negative items in sampling pools.
+  The key range is ``['uniform', 'popularity']``, which decides the distribution of negative items in sampling pools. In addition, we also support dynamic negative sampling ``['dynamic']``.
   ``uniform`` means uniformly select negative items while ``popularity`` means select negative items based on 
   their popularity (Counter(item) in `.inter` file). Note that if your data is labeled, you need to set this parameter as ``None``.
   The default value of this parameter is ``{'uniform': 1}``. 
+  When dynamic negative sampling, ``dynamic`` decides the number of candidate negative items. For example, ``{'uniform': 1, 'dynamic': 2}`` means sampling 2 items for each positive item uniformly, and dynamically choosing the item with the higher score as the selected negative item. In particular, ``'uniform': 1`` means that a positive item pairs with one negative item, and ``'dynamic': 2`` means dynamically selecting each negative item from two candidates.
 - ``eval_step (int)`` : The number of training epochs before an evaluation
   on the valid dataset. If it is less than 1, the model will not be
   evaluated on the valid dataset. Defaults to ``1``.

recbole/config/configurator.py

@@ -354,19 +354,22 @@ def _set_train_neg_sample_args(self):
         else:
             if not isinstance(neg_sampling, dict):
                 raise ValueError(f"neg_sampling:[{neg_sampling}] should be a dict.")
-            if len(neg_sampling) > 1:
-                raise ValueError(f"the len of neg_sampling [{neg_sampling}] should be 1.")
 
             distribution = list(neg_sampling.keys())[0]
             sample_num = neg_sampling[distribution]
             if distribution not in ['uniform', 'popularity']:
                 raise ValueError(f"The distribution [{distribution}] of neg_sampling "
                                  f"should in ['uniform', 'popularity']")
 
+            dynamic = 'none'
+            if 'dynamic' in neg_sampling.keys():
+                dynamic = neg_sampling['dynamic']
+
             self.final_config_dict['train_neg_sample_args'] = {
                 'strategy': 'by',
                 'by': sample_num,
-                'distribution': distribution
+                'distribution': distribution,
+                'dynamic': dynamic
             }
 
     def _set_eval_neg_sample_args(self):

recbole/data/dataloader/abstract_dataloader.py

@@ -13,6 +13,7 @@
 """
 
 import math
+import copy
 from logging import getLogger
 
 import torch
@@ -45,7 +46,7 @@ def __init__(self, config, dataset, sampler, shuffle=False):
         self.logger = getLogger()
         self.dataset = dataset
         self.sampler = sampler
-        self.batch_size = self.step = None
+        self.batch_size = self.step = self.model = None
         self.shuffle = shuffle
         self.pr = 0
         self._init_batch_size_and_step()
@@ -154,7 +155,23 @@ def _set_neg_sample_args(self, config, dataset, dl_format, neg_sample_args):
             raise ValueError(f'`neg_sample_args` [{self.neg_sample_args["strategy"]}] is not supported!')
 
     def _neg_sampling(self, inter_feat):
-        if self.neg_sample_args['strategy'] == 'by':
+        if 'dynamic' in self.neg_sample_args.keys() and self.neg_sample_args['dynamic'] != 'none':
+            candidate_num = self.neg_sample_args['dynamic']
+            user_ids = inter_feat[self.uid_field]
+            item_ids = inter_feat[self.iid_field]
+            neg_candidate_ids = self.sampler.sample_by_user_ids(user_ids, item_ids, self.neg_sample_num * candidate_num)
+            self.model.eval()
+            interaction = copy.deepcopy(inter_feat).to(self.model.device)
+            interaction = interaction.repeat(self.neg_sample_num * candidate_num)
+            neg_item_feat = Interaction({self.iid_field: neg_candidate_ids.to(self.model.device)})
+            interaction.update(neg_item_feat)
+            scores = self.model.predict(interaction).reshape(candidate_num, -1)            
+            indices = torch.max(scores, dim=0)[1].detach()
+            neg_candidate_ids = neg_candidate_ids.reshape(candidate_num, -1)
+            neg_item_ids = neg_candidate_ids[indices, [i for i in range(neg_candidate_ids.shape[1])]].view(-1)
+            self.model.train()
+            return self.sampling_func(inter_feat, neg_item_ids)
+        elif self.neg_sample_args['strategy'] == 'by':
             user_ids = inter_feat[self.uid_field]
             item_ids = inter_feat[self.iid_field]
             neg_item_ids = self.sampler.sample_by_user_ids(user_ids, item_ids, self.neg_sample_num)
@@ -179,3 +196,6 @@ def _neg_sample_by_point_wise_sampling(self, inter_feat, neg_item_ids):
         labels[:pos_inter_num] = 1.0
         new_data.update(Interaction({self.label_field: labels}))
         return new_data
+
+    def get_model(self, model):
+        self.model = model

recbole/data/dataloader/knowledge_dataloader.py

@@ -182,3 +182,8 @@ def set_mode(self, state):
         if state not in set(KGDataLoaderState):
             raise NotImplementedError(f'Kg data loader has no state named [{self.state}].')
         self.state = state
+
+    def get_model(self, model):
+        """Let the general_dataloader get the model, used for dynamic sampling.
+        """
+        self.general_dataloader.get_model(model)

recbole/data/dataset/dataset.py

@@ -433,7 +433,7 @@ def _load_feat(self, filepath, source):
             return None
 
         df = pd.read_csv(
-            filepath, delimiter=self.config['field_separator'], usecols=usecols, dtype=dtype, encoding=encoding
+            filepath, delimiter=self.config['field_separator'], usecols=usecols, dtype=dtype, encoding=encoding, engine='python'
         )
         df.columns = columns
 

recbole/model/abstract_recommender.py

@@ -124,6 +124,9 @@ def __init__(self, config, dataset):
         self.max_seq_length = config['MAX_ITEM_LIST_LENGTH']
         self.n_items = dataset.num(self.ITEM_ID)
 
+        # load parameters info
+        self.device = config['device']
+
     def gather_indexes(self, output, gather_index):
         """Gathers the vectors at the specific positions over a minibatch"""
         gather_index = gather_index.view(-1, 1, 1).expand(-1, -1, output.shape[-1])

recbole/model/sequential_recommender/hrm.py

@@ -156,7 +156,6 @@ def predict(self, interaction):
         test_item = interaction[self.ITEM_ID]
         user = interaction[self.USER_ID]
         seq_output = self.forward(item_seq, user, seq_item_len)
-        seq_output = seq_output.repeat(1, self.embedding_size)
         test_item_emb = self.item_embedding(test_item)
         scores = torch.mul(seq_output, test_item_emb).sum(dim=1)
 

recbole/trainer/trainer.py

@@ -308,7 +308,8 @@ def fit(self, train_data, valid_data=None, verbose=True, saved=True, show_progre
             self._save_checkpoint(-1)
 
         self.eval_collector.data_collect(train_data)
-
+        if 'dynamic' in self.config['train_neg_sample_args'].keys() and self.config['train_neg_sample_args']['dynamic'] != 'none':
+            train_data.get_model(self.model)
         for epoch_idx in range(self.start_epoch, self.epochs):
             # train
             training_start_time = time()

tests/model/test_model_auto.py

@@ -41,6 +41,16 @@ def test_bpr(self):
         }
         quick_test(config_dict)
 
+    def test_bpr_with_dns(self):
+        config_dict = {
+            'model': 'BPR',
+            'neg_sampling': {
+                'uniform': 1,
+                'dynamic': 2
+            }
+        }
+        quick_test(config_dict)
+
     def test_neumf(self):
         config_dict = {
             'model': 'NeuMF',
@@ -656,17 +666,29 @@ def test_bert4rec(self):
             'model': 'BERT4Rec',
             'neg_sampling': None
         }
-        objective_function(config_dict=config_dict,
-                           config_file_list=config_file_list, saved=False)
+        quick_test(config_dict)
 
     def test_bert4rec_with_BPR_loss_and_swish(self):
         config_dict = {
             'model': 'BERT4Rec',
             'loss_type': 'BPR',
             'hidden_act': 'swish'
         }
-        objective_function(config_dict=config_dict,
-                           config_file_list=config_file_list, saved=False)
+        quick_test(config_dict)
+
+    def test_lightsans(self):
+        config_dict = {
+            'model': 'LightSANs',
+            'neg_sampling': None
+        }
+        quick_test(config_dict)
+
+    def test_lightsans_with_BPR_loss(self):
+        config_dict = {
+            'model': 'LightSANs',
+            'loss_type': 'BPR',
+        }
+        quick_test(config_dict)
 
     # def test_gru4reckg(self):
     #     config_dict = {