---
license: other
pipeline_tag: token-classification
tags:
  - biology
  - RNA
  - Torsional
  - Angles
---
# `RNA-TorsionBERT`

## Model Description

`RNA-TorsionBERT` is a 331 MB parameter BERT-based language model that predicts RNA torsional and pseudo-torsional angles from the sequence. 

`RNA-TorsionBERT` is a DNABERT model that was pre-trained on ~4200 RNA structures before being fine-tuned on 185 non-redundant structures. 

It provides an improvement of MAE of 6.2° over the previous state-of-the-art model, SPOT-RNA-1D, on the Test Set (composed of RNA-Puzzles and CASP-RNA).


| Model            | alpha | beta  | gamma | delta | epsilon | zeta  | chi   | eta | theta | 
|------------------|----------|-------|-------|-------|---------|-------|-------|-------|-------| 
| **RNA-TorsionBERT**  | 37.3 | 19.6 | 29.4 | 13.6 | 16.6 | 26.6 | 14.7 | 20.1 | 25.4 | 
| SPOT-RNA-1D        | 45.7 | 23 | 33.6 | 19 | 21.1 | 34.4 | 19.3 | 28.9 | 33.9 | 

**Key Features**
* Torsional and Pseudo-torsional angles prediction
* Predict sequences up to 512 nucleotides

## Usage

Get started generating text with `RNA-TorsionBERT` by using the following code snippet:

```python
from transformers import AutoModel, AutoTokenizer

tokenizer = AutoTokenizer.from_pretrained("sayby/rna_torsionbert", trust_remote_code=True)
model = AutoModel.from_pretrained("sayby/rna_torsionbert", trust_remote_code=True)

sequence = "ACG CGG GGT GTT"
params_tokenizer = {
    "return_tensors": "pt",
    "padding": "max_length",
    "max_length": 512,
    "truncation": True,
}
inputs = tokenizer(sequence, **params_tokenizer)
output = model(inputs)["logits"]
```

- Please note that it was fine-tuned from a DNABERT-3 model and therefore the tokenizer is the same as the one used for DNABERT. Nucleotide `U` should therefore be replaced by `T` in the input sequence.
- The output is the sinus and the cosine for each angle. The angles are in the following order: `alpha`, `beta`, `gamma`, `delta`, `epsilon`, `zeta`, `chi`, `eta`, `theta`.

To convert the predictions into angles, you can use the following code snippet:

```python
from typing import Optional

import numpy as np

ANGLES_ORDER = [ "alpha", "beta", "gamma", "delta", "epsilon", "zeta", "chi", "eta", "theta" ]

def convert_sin_cos_to_angles(output: np.ndarray, input_ids: Optional[np.ndarray] = None):
    """
    Convert the raw predictions of the RNA-TorsionBERT into angles.
    It converts the cos and sinus into angles using:
        alpha = arctan(sin(alpha)/cos(alpha))
    :param output: Dictionary with the predictions of the RNA-TorsionBERT per angle
    :param input_ids: the input_ids of the RNA-TorsionBERT. It allows to only select the of the sequence,
        and not the special tokens.
    :return: a np.ndarray with the angles for the sequence
    """
    if input_ids is not None:
        output[ (input_ids == 0) | (input_ids == 1) | (input_ids == 2) | (input_ids == 3) | (input_ids == 4) ] = np.nan
    pair_indexes, impair_indexes = np.arange(0, output.shape[-1], 2), np.arange(
        1, output.shape[-1], 2
    )
    sin, cos = output[:, :, impair_indexes], output[:, :, pair_indexes]
    tan = np.arctan2(sin, cos)
    angles = np.degrees(tan)
    return angles

output = output.cpu().detach().numpy()
input_ids = inputs["input_ids"].cpu().detach().numpy()
real_angles = convert_sin_cos_to_angles(output, input_ids)
```