How to Use the RoBERTa Model for Thai POS-Tagging and Dependency Parsing

Aug 20, 2024 | Educational

In the realm of natural language processing, the RoBERTa model pre-trained on Thai texts stands out for its effectiveness in Part-of-Speech (POS) tagging and dependency parsing. This article will guide you on how to utilize this powerful model for tagging and parsing Thai language constructs effortlessly.

Model Overview

The roberta-base-thai-syllable-ud-goeswith model is a sophisticated RoBERTa variant specifically designed for Thai, simplified to enhance understanding. This model has been pre-trained on data from Thai Wikipedia texts, leveraging semantic structures to improve the performance of linguistic tasks.

How to Implement the Model

To start using the model, follow these steps:

  • First, you’ll need to ensure you have the required libraries installed:
  • pip install transformers torch ufal.chu_liu_edmonds
  • Next, implement the model as follows:
class UDgoeswith(object):
    def __init__(self, bert):
        from transformers import AutoTokenizer, AutoModelForTokenClassification
        self.tokenizer = AutoTokenizer.from_pretrained(bert)
        self.model = AutoModelForTokenClassification.from_pretrained(bert)
    
    def __call__(self, text):
        import numpy, torch, ufal.chu_liu_edmonds
        w = self.tokenizer(text, return_offsets_mapping=True)
        v = w['input_ids']
        x = [v[0:i] + [self.tokenizer.mask_token_id] + v[i + 1:] + [j] for i, j in enumerate(v[1:-1], 1)]
        with torch.no_grad():
            e = self.model(input_ids=torch.tensor(x)).logits.numpy()[:, 1:-2, :]
        r = [1 if i == 0 else -1 if j.endswith('root') else 0 for i,j in sorted(self.model.config.id2label.items())]
        e += numpy.where(numpy.add.outer(numpy.identity(e.shape[0]), r) == 0, 0, numpy.nan)
        
        g = self.model.config.label2id['X_goeswith']
        r = numpy.tri(e.shape[0])
        for i in range(e.shape[0]):
            for j in range(i + 2, e.shape[1]):
                r[i,j] = r[i,j-1] if numpy.nanargmax(e[i,j-1])==g else 1
        e[:,:,g] += numpy.where(r == 0, 0, numpy.nan)
        
        m = numpy.full((e.shape[0] + 1, e.shape[1] + 1), numpy.nan)
        m[1:, 1:] = numpy.nanmax(e, axis=2).transpose()
        p = numpy.zeros(m.shape)
        p[1:, 1:] = numpy.nanargmax(e, axis=2).transpose()
        
        for i in range(1, m.shape[0]):
            m[i, 0], m[i, i], p[i, 0] = m[i, i], numpy.nan, p[i, i]
        
        h = ufal.chu_liu_edmonds.chu_liu_edmonds(m)[0]
        if [0 for i in h if i == 0] != [0]:
            m[:, 0] += numpy.where(m[:, 0] == numpy.nanmax(m[[i for i,j in enumerate(h) if j == 0], 0]), 0, numpy.nan)
            m[[i for i,j in enumerate(h) if j == 0]] += [0 if i == 0 or j == 0 else numpy.nan for i, j in enumerate(h)]
            h = ufal.chu_liu_edmonds.chu_liu_edmonds(m)[0]
        
        u = ''
        w = [(s, e) for s,e in w['offset_mapping'] if e]
        for i, (s, e) in enumerate(w, 1):
            q = self.model.config.id2label[p[i, h[i]]].split()
            u += ' '.join([str(i), text[s:e], q[0], q[1], str(h[i]), q[-1]]) + '\n'
        return u

nlp = UDgoeswith('KoichiYasuokaroberta-base-thai-syllable-ud-goeswith')
print(nlp('หลายหัวดีกว่าหัวเดียว'))

Understanding the Code through an Analogy

Think of the implementation as a recipe to create a specific dish – in this case, the dish is understanding a sentence in Thai.

  • The __init__ method is akin to prepping your kitchen and gathering all the necessary ingredients (libraries and components).
  • The __call__ method serves as the main cooking process where raw data (text) is converted into structured information (POS tags and dependencies).
  • Imagine the tokenizer as a chef chopping vegetables into manageable pieces, while each step taken in the code broadens this segmentation process until the dish is perfectly plated with all its components (the parsed sentence).
  • Finally, the output is similar to a well-prepared dish served at a table, ready to be enjoyed and understood.

Troubleshooting

If you encounter issues while running the model, here are some troubleshooting steps you can take:

  • Ensure the libraries are up-to-date and correctly installed.
  • Check the input format; make sure you are passing strings correctly.
  • If any unexpected errors arise, verify the model name and configurations by visiting the source documentation on Hugging Face.

For more insights, updates, or to collaborate on AI development projects, stay connected with fxis.ai.

Conclusion

By implementing this RoBERTa model, you can effectively perform POS tagging and dependency parsing for Thai text, opening up new avenues for linguistic analysis and understanding.

At fxis.ai, we believe that such advancements are crucial for the future of AI, as they enable more comprehensive and effective solutions. Our team is continually exploring new methodologies to push the envelope in artificial intelligence, ensuring that our clients benefit from the latest technological innovations.

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