---
library_name: transformers
license: mit
datasets:
- rajpurkar/squad_v2
language:
- en
base_model:
- answerdotai/ModernBERT-base
pipeline_tag: question-answering
---

# ModernBERT-base-squad2

ModernBERT fine-tuned for extractive question answering tasks. Use this model to extract specific spans of text within a given context that directly answer questions.

- Base Model: `answerdotai/ModernBERT-base`
- Fine-tuned on: SQuAD 2.0 dataset
- Use: Extractive question answering

---

# Usage
```python
from transformers import AutoTokenizer, AutoModel
import torch.nn.functional as F
import torch

def predict_answers(batch, model, tokenizer, device):
    inputs = tokenizer(
        [item["question"] for item in batch],
        [item["context"] for item in batch],
        return_tensors="pt",
        max_length=512,
        truncation=True,
        padding="max_length",
    ).to(device)

    with torch.no_grad():
        outputs = model(**inputs)

    start_probs = F.softmax(outputs.start_logits, dim=-1)
    end_probs = F.softmax(outputs.end_logits, dim=-1)
    start_indices = torch.argmax(start_probs, dim=-1)
    end_indices = torch.argmax(end_probs, dim=-1)

    return [
        (
            tokenizer.decode(inputs["input_ids"][i][start:end + 1], skip_special_tokens=True),
            (start_probs[i, start] * end_probs[i, end]).item(),
        )
        for i, (start, end) in enumerate(zip(start_indices, end_indices))
    ]

model_id = "smangla/ModernBERT-base-squad2"
tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModel.from_pretrained(model_id, trust_remote_code=True)
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
model.to(device)

batch = [
    {"question": "What is the capital of France?", "context": "Paris is the capital of France."},
    {"question": "Who wrote Hamlet?", "context": "William Shakespeare wrote the play Hamlet."},
]

results = predict_answers(batch, model, tokenizer, device)

for i, (answer, prob) in enumerate(results):
    print(f"Question {i + 1}: {batch[i]['question']}")
    print(f"Answer: {answer}")
    print(f"Probability: {prob:.4f}")
```

Output:
```
Question 1: What is the capital of France?
Answer: Paris
Probability: 0.9929
Question 2: Who wrote Hamlet?
Answer: William Shakespeare
Probability: 0.9995
```

---

# Metrics
Evaluation results using the official evaluation script on SQuAD 2.0 dev set:

```json
{
  "exact": 80.29141750189505,
  "f1": 83.22890970115323,
  "total": 11873,
  "HasAns_exact": 72.08164642375169,
  "HasAns_f1": 77.96505480462089,
  "HasAns_total": 5928,
  "NoAns_exact": 88.47771236333053,
  "NoAns_f1": 88.47771236333053,
  "NoAns_total": 5945
}
```
---

# Limitations
- The model solely extracts answers from the input context to generate answers and does not use external knowledge.

---

# Training Details
- **Dataset:** SQuAD 2.0 ([https://huggingface.co/datasets/rajpurkar/squad_v2](https://huggingface.co/datasets/rajpurkar/squad_v2))
- **Epochs:** 4
- **Batch Size:** 32
- **Scheduler**: Linear
- **Learning Rate:** 5e-5
- **Weight decay:** 0.01
- **Warmup ratio:** 0.6

---