mBART support for run_summarization.py (#15125)

* Update run_summarization.py

* Fixed languages and added missing code

* fixed obj, docs, removed source_lang and target_lang

* make style, run_summarization.py reformatted

examples/pytorch/summarization/run_summarization.py

@@ -37,6 +37,10 @@ from transformers import (
     AutoTokenizer,
     DataCollatorForSeq2Seq,
     HfArgumentParser,
+    MBart50Tokenizer,
+    MBart50TokenizerFast,
+    MBartTokenizer,
+    MBartTokenizerFast,
     Seq2SeqTrainer,
     Seq2SeqTrainingArguments,
     set_seed,
@@ -64,6 +68,9 @@ except (LookupError, OSError):
     with FileLock(".lock") as lock:
         nltk.download("punkt", quiet=True)
 
+# A list of all multilingual tokenizer which require lang attribute.
+MULTILINGUAL_TOKENIZERS = [MBartTokenizer, MBartTokenizerFast, MBart50Tokenizer, MBart50TokenizerFast]
+
 
 @dataclass
 class ModelArguments:
@@ -114,6 +121,8 @@ class DataTrainingArguments:
     Arguments pertaining to what data we are going to input our model for training and eval.
     """
 
+    lang: str = field(default=None, metadata={"help": "Language id for summarization."})
+
     dataset_name: Optional[str] = field(
         default=None, metadata={"help": "The name of the dataset to use (via the datasets library)."}
     )
@@ -217,12 +226,24 @@ class DataTrainingArguments:
         },
     )
     source_prefix: Optional[str] = field(
-        default=None, metadata={"help": "A prefix to add before every source text (useful for T5 models)."}
+        default="", metadata={"help": "A prefix to add before every source text (useful for T5 models)."}
+    )
+
+    forced_bos_token: Optional[str] = field(
+        default=None,
+        metadata={
+            "help": "The token to force as the first generated token after the decoder_start_token_id."
+            "Useful for multilingual models like mBART where the first generated token"
+            "needs to be the target language token (Usually it is the target language token)"
+        },
     )
 
     def __post_init__(self):
         if self.dataset_name is None and self.train_file is None and self.validation_file is None:
             raise ValueError("Need either a dataset name or a training/validation file.")
+        elif self.lang is None:
+            raise ValueError("Need to specify the language.")
+
         else:
             if self.train_file is not None:
                 extension = self.train_file.split(".")[-1]
@@ -370,6 +391,12 @@ def main():
 
     model.resize_token_embeddings(len(tokenizer))
 
+    if model.config.decoder_start_token_id is None and isinstance(tokenizer, (MBartTokenizer, MBartTokenizerFast)):
+        if isinstance(tokenizer, MBartTokenizer):
+            model.config.decoder_start_token_id = tokenizer.lang_code_to_id[data_args.lang]
+        else:
+            model.config.decoder_start_token_id = tokenizer.convert_tokens_to_ids(data_args.lang)
+
     if model.config.decoder_start_token_id is None:
         raise ValueError("Make sure that `config.decoder_start_token_id` is correctly defined")
 
@@ -406,6 +433,21 @@ def main():
         logger.info("There is nothing to do. Please pass `do_train`, `do_eval` and/or `do_predict`.")
         return
 
+    if isinstance(tokenizer, tuple(MULTILINGUAL_TOKENIZERS)):
+        assert (
+            data_args.lang is not None
+        ), f"{tokenizer.__class__.__name__} is a multilingual tokenizer which requires --lang argument"
+
+        tokenizer.src_lang = data_args.lang
+        tokenizer.tgt_lang = data_args.lang
+
+        # For multilingual translation models like mBART-50 and M2M100 we need to force the target language token
+        # as the first generated token. We ask the user to explicitly provide this as --forced_bos_token argument.
+        forced_bos_token_id = (
+            tokenizer.lang_code_to_id[data_args.forced_bos_token] if data_args.forced_bos_token is not None else None
+        )
+        model.config.forced_bos_token_id = forced_bos_token_id
+
     # Get the column names for input/target.
     dataset_columns = summarization_name_mapping.get(data_args.dataset_name, None)
     if data_args.text_column is None:
@@ -436,14 +478,16 @@ def main():
         )
 
     def preprocess_function(examples):
-
         # remove pairs where at least one record is None
+
         inputs, targets = [], []
         for i in range(len(examples[text_column])):
             if examples[text_column][i] is not None and examples[summary_column][i] is not None:
                 inputs.append(examples[text_column][i])
                 targets.append(examples[summary_column][i])
 
+        inputs = examples[text_column]
+        targets = examples[summary_column]
         inputs = [prefix + inp for inp in inputs]
         model_inputs = tokenizer(inputs, max_length=data_args.max_source_length, padding=padding, truncation=True)
 
@@ -637,6 +681,9 @@ def main():
         else:
             kwargs["dataset"] = data_args.dataset_name
 
+    if data_args.lang is not None:
+        kwargs["language"] = data_args.lang
+
     if training_args.push_to_hub:
         trainer.push_to_hub(**kwargs)
     else: