transformers

3dcb748e - Added data collator for permutation (XLNet) language modeling and related calls (#5522)

Added data collator for permutation (XLNet) language modeling and related calls (#5522) * Added data collator for XLNet language modeling and related calls Added DataCollatorForXLNetLanguageModeling in data/data_collator.py to generate necessary inputs for language modeling training with XLNetLMHeadModel. Also added related arguments, logic and calls in examples/language-modeling/run_language_modeling.py. Resolves: #4739, #2008 (partially) * Changed name to `DataCollatorForPermutationLanguageModeling` Changed the name of `DataCollatorForXLNetLanguageModeling` to the more general `DataCollatorForPermutationLanguageModelling`. Removed the `--mlm` flag requirement for the new collator and defined a separate `--plm_probability` flag for its use. CTRL uses a CLM loss just like GPT and GPT-2, so should work out of the box with this script (provided `past` is taken care of similar to `mems` for XLNet). Changed calls and imports appropriately. * Added detailed comments, changed variable names Added more detailed comments to `DataCollatorForPermutationLanguageModeling` in `data/data_collator.py` to explain working. Also cleaned up variable names and made them more informative. * Added tests for new data collator Added tests in `tests/test_trainer.py` for DataCollatorForPermutationLanguageModeling based on those in DataCollatorForLanguageModeling. A specific test has been added to check for odd-length sequences. * Fixed styling issues