From 398d229910f02dbddfd4659ee53d5b570ea6a14c Mon Sep 17 00:00:00 2001
From: Desjajja <DengXiangyu1126@outlook.com>
Date: Mon, 7 Aug 2023 15:33:48 +0800
Subject: [PATCH] Add a text translation example (#1283)

---
 examples/text_translation.py | 120 +++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 examples/text_translation.py

diff --git a/examples/text_translation.py b/examples/text_translation.py
new file mode 100644
index 00000000..61f43baf
--- /dev/null
+++ b/examples/text_translation.py
@@ -0,0 +1,120 @@
+import numpy as np
+import torch
+from datasets import load_dataset
+from torchtext.data.metrics import bleu_score
+from transformers import AutoTokenizer, T5ForConditionalGeneration
+
+from mmengine.evaluator import BaseMetric
+from mmengine.model import BaseModel
+from mmengine.runner import Runner
+
+tokenizer = AutoTokenizer.from_pretrained('t5-small')
+
+
+class MMT5ForTranslation(BaseModel):
+
+    def __init__(self, model):
+        super().__init__()
+        self.model = model
+
+    def forward(self, label, input_ids, attention_mask, mode):
+        if mode == 'loss':
+            output = self.model(
+                input_ids=input_ids,
+                attention_mask=attention_mask,
+                labels=label)
+            return {'loss': output.loss}
+        elif mode == 'predict':
+            output = self.model.generate(input_ids)
+            return output, label
+
+
+def post_process(preds, labels):
+    preds = tokenizer.batch_decode(preds, skip_special_tokens=True)
+    labels = torch.where(labels != -100, labels, tokenizer.pad_token_id)
+    labels = tokenizer.batch_decode(labels, skip_special_tokens=True)
+    decoded_preds = [pred.split() for pred in preds]
+    decoded_labels = [[label.split()] for label in labels]
+    return decoded_preds, decoded_labels
+
+
+class Accuracy(BaseMetric):
+
+    def process(self, data_batch, data_samples):
+        outputs, labels = data_samples
+        decoded_preds, decoded_labels = post_process(outputs, labels)
+        score = bleu_score(decoded_preds, decoded_labels)
+        prediction_lens = torch.tensor([
+            torch.count_nonzero(pred != tokenizer.pad_token_id)
+            for pred in outputs
+        ],
+                                       dtype=torch.float64)
+
+        gen_len = torch.mean(prediction_lens).item()
+        self.results.append({
+            'gen_len': gen_len,
+            'bleu': score,
+        })
+
+    def compute_metrics(self, results):
+        return dict(
+            gen_len=np.mean([item['gen_len'] for item in results]),
+            bleu_score=np.mean([item['bleu'] for item in results]),
+        )
+
+
+def collate_fn(data):
+    prefix = 'translate English to French: '
+    input_sequences = [prefix + item['translation']['en'] for item in data]
+    target_sequences = [item['translation']['fr'] for item in data]
+    input_dict = tokenizer(
+        input_sequences,
+        padding='longest',
+        return_tensors='pt',
+    )
+
+    label = tokenizer(
+        target_sequences,
+        padding='longest',
+        return_tensors='pt',
+    ).input_ids
+    label[label ==
+          tokenizer.pad_token_id] = -100  # ignore contribution to loss
+    return dict(
+        label=label,
+        input_ids=input_dict.input_ids,
+        attention_mask=input_dict.attention_mask)
+
+
+def main():
+    model = T5ForConditionalGeneration.from_pretrained('t5-small')
+
+    books = load_dataset('opus_books', 'en-fr')
+    books = books['train'].train_test_split(test_size=0.2)
+    train_set, test_set = books['train'], books['test']
+
+    train_loader = dict(
+        batch_size=16,
+        dataset=train_set,
+        sampler=dict(type='DefaultSampler', shuffle=True),
+        collate_fn=collate_fn)
+    test_loader = dict(
+        batch_size=32,
+        dataset=test_set,
+        sampler=dict(type='DefaultSampler', shuffle=False),
+        collate_fn=collate_fn)
+    runner = Runner(
+        model=MMT5ForTranslation(model),
+        train_dataloader=train_loader,
+        val_dataloader=test_loader,
+        optim_wrapper=dict(optimizer=dict(type=torch.optim.Adam, lr=2e-5)),
+        train_cfg=dict(by_epoch=True, max_epochs=2, val_interval=1),
+        val_cfg=dict(),
+        work_dir='t5_work_dir',
+        val_evaluator=dict(type=Accuracy))
+
+    runner.train()
+
+
+if __name__ == '__main__':
+    main()