add avg ppl

scripts/cal_ppl.py

@@ -54,6 +54,7 @@ def cal_ppl(
 
     dataloader = DataLoader(trainset, batch_size, shuffle=False, collate_fn=data_collator, pin_memory=True)
     criterion = torch.nn.CrossEntropyLoss(reduction="none")
+    total_ppl = 0
     perplexities = []
     batch: Dict[str, "torch.Tensor"]
     with torch.no_grad():
@@ -68,11 +69,13 @@ def cal_ppl(
             token_logps: "torch.Tensor" = criterion(flatten_logits, flatten_labels)
             token_logps = token_logps.contiguous().view(shift_logits.size(0), -1)
             sentence_logps = (token_logps * loss_mask).sum(-1) / loss_mask.sum(-1)
+            total_ppl += sentence_logps.exp().sum().item()
             perplexities.extend(sentence_logps.exp().tolist())
 
     with open(save_name, "w", encoding="utf-8") as f:
         json.dump(perplexities, f, indent=2)
 
+    print("Average perplexity is {:.2f}".format(total_ppl / len(perplexities)))
     print("Perplexities have been saved at {}.".format(save_name))