Add model card

README.md

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+---
+license: apache-2.0
+tags:
+datasets:
+- code_search_net
+---
+
+# CodeT5 (small-sized model) 
+
+Pre-trained CodeT5 model. It was introduced in the paper [CodeT5: Identifier-aware Unified Pre-trained Encoder-Decoder Models
+for Code Understanding and Generation](https://arxiv.org/abs/2109.00859) by Yue Wang, Weishi Wang, Shafiq Joty, Steven C.H. Hoi and first released in [this repository](https://github.com/salesforce/CodeT5). 
+
+Disclaimer: The team releasing CodeT5 did not write a model card for this model so this model card has been written by the Hugging Face team (more specifically, [nielsr](https://huggingface.co/nielsr)).
+
+## Model description
+
+From the abstract:
+
+"We present CodeT5, a unified pre-trained encoder-decoder Transformer model that better leverages the code semantics conveyed from the developer-assigned identifiers. Our model employs a unified framework to seamlessly support both code understanding and generation tasks and allows for multi-task learning. Besides, we propose a novel identifier-aware pre-training task that enables the model to distinguish which code tokens are identifiers and to recover them when they are masked. Furthermore, we propose to exploit the user-written code comments with a bimodal dual generation task for better NL-PL alignment. Comprehensive experiments show that CodeT5 significantly outperforms prior methods on understanding tasks such as code defect detection and clone detection, and generation tasks across various directions including PL-NL, NL-PL, and PL-PL. Further analysis reveals that our model can better capture semantic information from code."
+
+## Intended uses & limitations
+
+This repository contains the pre-trained model only, so you can use this model for masked span prediction, as shown in the code example below. However, the main use of this model is to fine-tune it for a downstream task of interest, such as:
+* code summarization
+* code generation
+* code translation
+* code refinement
+* code defect detection
+* code clone detection. 
+
+See the [model hub](https://huggingface.co/models?search=salesforce/codet) to look for fine-tuned versions on a task that interests you.
+
+### How to use
+
+Here is how to use this model:
+
+```python
+from transformers import RobertaTokenizer, T5ForConditionalGeneration
+
+tokenizer = RobertaTokenizer.from_pretrained('Salesforce/codet5-small')
+model = T5ForConditionalGeneration.from_pretrained('Salesforce/codet5-small')
+
+text = "def greet(user): print(f'hello <extra_id_0>!') </s>"
+inputs = tokenizer(text, return_tensors="pt").input_ids
+
+# simply generate a single sequence
+generated_ids = model.generate(input_ids, max_length=8)
+print(tokenizer.decode(generated_ids[0], skip_special_tokens=True))
+# this prints {user.name}
+
+# or, generating 20 sequences with maximum length set to 10
+outputs = model.generate(input_ids=input_ids, 
+                          num_beams=200, num_return_sequences=20,
+                          max_length=10)
+
+_0_index = text.index('<extra_id_0>')
+_result_prefix = text[:_0_index]
+_result_suffix = text[_0_index+12:]  # 12 is the length of <extra_id_0>
+
+def _filter(output, end_token='<extra_id_1>'):
+    # The first token is <pad> (indexed at 0), the second token is <s> (indexed at 1)
+    # and the third token is <extra_id_0> (indexed at 32099)
+    # So we only decode from the fourth generated id
+    _txt = tokenizer.decode(output[3:], skip_special_tokens=False, clean_up_tokenization_spaces=False)
+    if end_token in _txt:
+        _end_token_index = _txt.index(end_token)
+        return _result_prefix + _txt[:_end_token_index] + _result_suffix
+    else:
+        return _result_prefix + _txt + _result_suffix
+
+results = list(map(_filter, outputs))
+print(results)
+# this prints:
+#["def greet(user): print(f'hello {user.name} {user!') </s>",
+# "def greet(user): print(f'hello {user.username} {user!') </s>",
+# "def greet(user): print(f'hello {user.name}: {user!') </s>",
+# "def greet(user): print(f'hello {user}') print(f!') </s>",
+# "def greet(user): print(f'hello {user.name} �!') </s>",
+# "def greet(user): print(f'hello {user}') print ( f!') </s>",
+# "def greet(user): print(f'hello {user.username}: {user!') </s>",
+# "def greet(user): print(f'hello {user}' ) print(f!') </s>",
+# "def greet(user): print(f'hello {user.username} �!') </s>",
+# "def greet(user): print(f'hello {user.name}, {user!') </s>",
+# "def greet(user): print(f'hello {user.login} {user!') </s>",
+# "def greet(user): print(f'hello {user} →!') </s>",
+# "def greet(user): print(f'hello {user}!') print(!') </s>",
+# "def greet(user): print(f'hello {user.name} ({user!') </s>",
+# "def greet(user): print(f'hello {user.email} {user!') </s>",
+# "def greet(user): print(f'hello {user}!') print (!') </s>",
+# "def greet(user): print(f'hello {user.username}, {user!') </s>",
+# "def greet(user): print(f'hello {user}' ) print ( f!') </s>",
+# "def greet(user): print(f'hello {user.nickname} {!') </s>",
+# "def greet(user): print(f'hello {user} {user.name!') </s>"]
+```
+
+## Training data
+
+The CodeT5 model was pretrained on CodeSearchNet [Husain et al., 2019](https://arxiv.org/abs/1909.09436). Additionally, the authors collected two datasets of C/CSharp from [BigQuery1](https://console.cloud.google.com/marketplace/details/github/github-repos) to ensure that all downstream tasks have overlapped programming languages with the pre-training data. In total, around 8.35 million instances are used for pretraining. 
+
+## Training procedure
+
+### Preprocessing
+
+This model uses a code-specific BPE (Byte-Pair Encoding) tokenizer. One can prepare text (or code) for the model using RobertaTokenizer, with the files from this repository.
+
+## Evaluation results
+
+For evaluation results on several downstream benchmarks, we refer to the paper.
+
+### BibTeX entry and citation info
+
+```bibtex
+@misc{wang2021codet5,
+      title={CodeT5: Identifier-aware Unified Pre-trained Encoder-Decoder Models for Code Understanding and Generation}, 
+      author={Yue Wang and Weishi Wang and Shafiq Joty and Steven C. H. Hoi},
+      year={2021},
+      eprint={2109.00859},
+      archivePrefix={arXiv},
+      primaryClass={cs.CL}
+}
+```