Evaluation
Evaluated on a deterministic held-out set of 3,000 pairs (seed=42), decoded
greedily (do_sample=False, no repetition penalty), scored with sacreBLEU:
Table with columns: Direction, sacreBLEU, chrF| Direction | sacreBLEU | chrF |
|---|
| English → Egyptian | 23.83 | 51.94 |
| Egyptian → English | 33.90 | 53.01 |
Egyptian→English scores notably higher, as expected — English is more standardized
so a single reference captures more of the valid output space, whereas Egyptian
colloquial has many equally-correct spellings and phrasings. The saved weights are
the best checkpoint by validation loss (eval_loss=0.9297, epoch 2 of 3).
Decoding note: use plain greedy. A repetition penalty (1.2) was tested on
these 50M translation models and lowered BLEU by 5–12 points, because Arabic
legitimately repeats short particles that the penalty suppresses.
Example translations
Real greedy-decoded outputs from the held-out set:
English → Egyptian
Table with columns: English input, Model output (Egyptian)| English input | Model output (Egyptian) |
|---|
| Man, these things happen. Sometimes Liverpool loses the match, and other times Real Madrid wins it. | يا عم الحاجات دي بتحصل. ساعات ليفربول بيخسر الماتش، وساعات ريال مدريد بيكسبه. |
| I will be fine, don't worry | أنا هبقى كويس، ما تقلقش |
| I want grilled chicken, kofta on charcoal, and Pepsi. | عايز فراخ مشوية وكفتة على الفحم وبابسي. |
Egyptian → English
Table with columns: Egyptian input, Model output (English)| Egyptian input | Model output (English) |
|---|
| يا عم الحاجات دي بتحصل، ساعات ليفربول بتخسر الماتش وساعات ريال مدريد بيكسب. | Hey, these things happen, sometimes Liverpool loses the match and sometimes Real Madrid wins. |
| انا هبقى كويسة، ما تقلقيش | I'll be fine, don't worry |
| انا عايز فراخ مشوية وكفتة على الفحم وبيبسي. | I want grilled chicken, kofta, and chopped on charcoal. |
A larger set of 20 examples per direction (with references) is in
eval_bidirectional.json.
Usage
ChatML format. Pick the system prompt for the direction you want:
import torch
from transformers import AutoModelForCausalLM, AutoTokenizer
model_id = "oddadmix/50M-Egyptian-English-v1"
tok = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id, dtype=torch.bfloat16).to("cuda").eval()
SYS_TO_EGY = "أنت مترجم محترف. ترجم النص الإنجليزي إلى اللهجة المصرية العامية."
SYS_TO_EN = "You are a professional translator. Translate the Egyptian Arabic text into English."
def translate(text: str, system: str) -> str:
prompt = (
f"<|im_start|>system\n{system}<|im_end|>\n"
f"<|im_start|>user\n{text.strip()}<|im_end|>\n"
f"<|im_start|>assistant\n"
)
ids = tok(prompt, return_tensors="pt", add_special_tokens=False).to(model.device)
if tok.bos_token_id is not None:
bos = torch.tensor([[tok.bos_token_id]], device=model.device)
ids["input_ids"] = torch.cat([bos, ids["input_ids"]], dim=1)
ids["attention_mask"] = torch.cat([torch.ones_like(bos), ids["attention_mask"]], dim=1)
out = model.generate(**ids, max_new_tokens=256, do_sample=False,
eos_token_id=tok.eos_token_id, pad_token_id=tok.pad_token_id)
return tok.decode(out[0, ids["input_ids"].size(1):], skip_special_tokens=True).strip()
print(translate("I will be fine, don't worry", SYS_TO_EGY))
print(translate("انا هبقى كويسة، ما تقلقيش", SYS_TO_EN))
Training
- Base model:
oddadmix/50M-2048-Emhotob (Llama arch, ~51.8M params)
- Dataset:
oddadmix/egyptian-translation-dataset-2.9-openai-batch (135K rows, English/Arabic columns; Arabic = Egyptian colloquial)
- Method: HuggingFace
Trainer, ChatML, prompt-masked cross-entropy (loss only
on the assistant turn). Each row is exploded into two training examples (one per
direction, ~261K total). Two ChatML special tokens (<|im_start|>, <|im_end|>) were
added and embeddings resized.
- Hyperparameters: 3 epochs · effective batch 64 · LR 3e-4 (cosine, 5% warmup) ·
bf16 · max length 1024 ·
load_best_model_at_end on eval_loss.
- 132,282 train / 3,000 deterministic held-out (), scored both directions.
Out-of-domain evaluation — Egyptian Arabic Translation Benchmark
The results above are in-domain: a held-out split of the same corpus this model was
trained on. The numbers below are out-of-domain — the same model scored on the
Egyptian Arabic Translation Benchmark
(oddadmix/egyptian-arabic-translation-benchmark, 319 English→Egyptian pairs written by a different annotator with different
orthographic conventions).
Expect these to be substantially lower than the in-domain scores. That gap is the
generalization penalty, not a regression — both numbers are real, they measure different things.
Table with columns: Metric, Score| Metric | Score |
|---|
BLEU (evaluate, 0–1 — leaderboard metric) | 0.1113 |
| BLEU (sacrebleu, 0–100) | 11.13 |
| chrF | 44.41 |
| METEOR | 0.3482 |
Decoding is deterministic greedy (do_sample=False, no repetition penalty), using the
exact ChatML prompt format the model was trained with — the same protocol as every other
number in this study.
Where this rung sits
Table with columns: Model, Params, BLEU (hf), BLEU (sacre), chrF, METEOR| Model | Params | BLEU (hf) | BLEU (sacre) | chrF | METEOR |
|---|
| 5M v1 | 5.2M | 0.0000 | 0.19 | 13.00 | 0.0558 |
| 5M v2 | 5.2M | 0.0108 | 1.08 | 22.19 | 0.1352 |
| 10M v1 | 11.2M | 0.0313 |
Reading these numbers
BLEU understates quality on this set. Scoring is against a single reference, so a correct
translation that picks a different valid word is penalized — e.g. فريش vs the reference's
طازة for "fresh", or التليفون اللي ضاع vs تليفونها الضايع for "her lost phone". Both are
good Egyptian; only one matches the reference. chrF and METEOR track perceived quality more
closely here.
At 319 rows, differences of roughly 1–2 BLEU between adjacent rungs are within noise.
These are small models — 5M to 50M parameters, orders of magnitude below the large systems
typically evaluated on this benchmark. The result of interest is the scaling curve and
per-parameter efficiency, not absolute rank against models 100–1000× the size.
Limitations
- A 50M model: expect errors on rare / technical vocabulary, proper nouns, and
occasional drift on long inputs (see the "Haman"/"chopped" slips in the examples).
Everyday conversational text is handled well.
- Gender is disambiguated only from context; ambiguous inputs may default one way.
- Trained on conversational Egyptian ↔ English; other Arabic dialects and formal/
technical registers are out of scope.
License
Apache-2.0, inherited from the base model.