Replace -100s in predictions by the pad token (#22693)

* Replace -100s in predictions by the pad token

* Style

* Try to catch them all

examples/pytorch/question-answering/run_seq2seq_qa.py

@@ -26,6 +26,7 @@ from typing import List, Optional, Tuple
 
 import datasets
 import evaluate
+import numpy as np
 from datasets import load_dataset
 from trainer_seq2seq_qa import QuestionAnsweringSeq2SeqTrainer
 
@@ -614,6 +615,8 @@ def main():
         preds = outputs.predictions
         if isinstance(preds, tuple):
             preds = preds[0]
+        # Replace -100s used for padding as we can't decode them
+        preds = np.where(preds != -100, preds, tokenizer.pad_token_id)
         decoded_preds = tokenizer.batch_decode(preds, skip_special_tokens=True)
 
         # Build a map example to its corresponding features.