[run_generation] Fix generation with batch_size>1

examples/run_generation.py

@@ -79,7 +79,7 @@ def set_seed(args):
 def top_k_top_p_filtering(logits, top_k=0, top_p=0.0, filter_value=-float('Inf')):
     """ Filter a distribution of logits using top-k and/or nucleus (top-p) filtering
         Args:
-            logits: logits distribution shape (vocabulary size)
+            logits: logits distribution shape (batch size x vocabulary size)
             top_k > 0: keep only top k tokens with highest probability (top-k filtering).
             top_p > 0.0: keep the top tokens with cumulative probability >= top_p (nucleus filtering).
                 Nucleus filtering is described in Holtzman et al. (http://arxiv.org/abs/1904.09751)
@@ -138,13 +138,14 @@ def sample_sequence(model, length, context, num_samples=1, temperature=1, top_k=
             outputs = model(**inputs)  # Note: we could also use 'past' with GPT-2/Transfo-XL/XLNet/CTRL (cached hidden-states)
             next_token_logits = outputs[0][:, -1, :] / (temperature if temperature > 0 else 1.)
 
-            # reptition penalty from CTRL (https://arxiv.org/abs/1909.05858)
-            for _ in set(generated.view(-1).tolist()):
-                next_token_logits[_] /= repetition_penalty
+            # repetition penalty from CTRL (https://arxiv.org/abs/1909.05858)
+            for i in range(num_samples):
+                for _ in set(generated[i].tolist()):
+                    next_token_logits[i, _] /= repetition_penalty
                 
             filtered_logits = top_k_top_p_filtering(next_token_logits, top_k=top_k, top_p=top_p)
-            if temperature == 0: #greedy sampling:
-                next_token = torch.argmax(filtered_logits).unsqueeze(0)
+            if temperature == 0: # greedy sampling:
+                next_token = torch.argmax(filtered_logits, dim=-1).unsqueeze(-1)
             else:
                 next_token = torch.multinomial(F.softmax(filtered_logits, dim=-1), num_samples=1)
             generated = torch.cat((generated, next_token), dim=1)