What challenges arise when processing Thai text for classification?

The main challenges are missing spaces between words, ambiguous segmentation, combining marks and inconsistent input, informal spelling, loanwords and code-switching, limited or noisy labels, class imbalance and domain shift. Each must be represented in the evaluation set rather than handled only through generic preprocessing.

Why is Thai word segmentation difficult?

Thai normally does not put spaces between every word. Spaces often separate larger segments, while a character sequence can allow more than one plausible word boundary. Dictionary coverage, unknown terms and domain context therefore affect segmentation and downstream classification.

What is the best tokenizer for Thai text classification?

There is no universal best tokenizer. Compare a character baseline, a pinned Thai word tokenizer and a subword tokenizer on the same leakage-safe split and Thai-specific slices. Select the option that improves the end task while meeting latency, cost and maintainability requirements.

Is a Thai transformer always better than a linear classifier?

No. Thai-specific pretrained models can capture richer context, but character or word TF-IDF linear models may be competitive on bounded tasks and are cheaper to train, inspect and serve. Compare candidates with the same data, splits and metrics.

How should Thai text classification be evaluated?

Use group- or time-aware splits where needed, prevent duplicates and preprocessing leakage, and report per-class precision, recall, F1, confusion patterns and macro-F1. Add slices for Thai-only and mixed text, formal and informal language, input length, source, terminology and time.

How should Thai-English code-switching be handled?

Preserve both scripts, retain representative mixed-language examples and compare Thai-specific, multilingual or loanword-aware tokenization and models. Measure named entities, product terms and mixed-text errors separately rather than translating or deleting English by default.

Thai Text Classification

Thai Text Classification Challenges and How to Solve Them

The main challenges when processing Thai text for classification are missing spaces between words, ambiguous segmentation, combining marks and inconsistent Unicode input, spelling variation, English loanwords and code-switching, scarce or noisy labels, class

Ruskin Felix Barar19 December 2025Updated 4 October 202612 min read

Thai Text Classification Challenges and How to Solve Them

The main challenges when processing Thai text for classification are missing spaces between words, ambiguous segmentation, combining marks and