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---

license: mit
tags:
- sentiment-analysis
- text-classification
- electra
- pytorch
- transformers
---


# ELECTRA Base Classifier for Sentiment Analysis

This is an [ELECTRA base discriminator](https://huggingface.co/google/electra-base-discriminator) fine-tuned for sentiment analysis of reviews. It has a mean pooling layer and a classifier head (2 layers of 1024 dimension) with SwishGLU activation and dropout (0.3). It classifies text into three sentiment categories: 'negative' (0), 'neutral' (1), and 'positive' (2). It was fine-tuned on the [Sentiment Merged](https://huggingface.co/datasets/jbeno/sentiment_merged) dataset, which is a merge of Stanford Sentiment Treebank (SST-3), and DynaSent Rounds 1 and 2.


## Labels

The model predicts the following labels:

- `0`: negative
- `1`: neutral
- `2`: positive

## How to Use

### Install package

This model requires the classes in `electra_classifier.py`. You can download the file, or you can install the package from PyPI.

```bash

pip install electra-classifier

```

### Load classes and model
```python

# Install the package in a notebook

!pip install electra-classifier



# Import libraries

import torch

from transformers import AutoTokenizer

from electra_classifier import ElectraClassifier



# Load tokenizer and model

model_name = "jbeno/electra-base-classifier-sentiment"

tokenizer = AutoTokenizer.from_pretrained(model_name)

model = ElectraClassifier.from_pretrained(model_name)



# Set model to evaluation mode

model.eval()



# Run inference

text = "I love this restaurant!"

inputs = tokenizer(text, return_tensors="pt")



with torch.no_grad():

    logits = model(**inputs)

    predicted_class_id = torch.argmax(logits, dim=1).item()

    predicted_label = model.config.id2label[predicted_class_id]

    print(f"Predicted label: {predicted_label}")

```

## Requirements
- Python 3.7+
- PyTorch
- Transformers
- [electra-classifier](https://pypi.org/project/electra-classifier/) - Install with pip, or download electra_classifier.py



## Training Details



### Dataset



The model was trained on the [Sentiment Merged](https://huggingface.co/datasets/jbeno/sentiment_merged) dataset, which is a mix of Stanford Sentiment Treebank (SST-3), DynaSent Round 1, and DynaSent Round 2.



### Code



The code used to train the model can be found on GitHub:

- [jbeno/sentiment](https://github.com/jbeno/sentiment)

- [jbeno/electra-classifier](https://github.com/jbeno/electra-classifier)



### Research Paper



The research paper can be found here: [ELECTRA and GPT-4o: Cost-Effective Partners for Sentiment Analysis](https://github.com/jbeno/sentiment/research_paper.pdf)



### Performance Summary



- **Merged Dataset**

    - Macro Average F1: **79.29**

    - Accuracy: **79.69**

- **DynaSent R1**

    - Macro Average F1: **82.10**

    - Accuracy: **82.14**

- **DynaSent R2**

    - Macro Average F1: **71.83**

    - Accuracy: **71.94**

- **SST-3**

    - Macro Average F1: **69.95**

    - Accuracy: **78.24**



## Model Architecture



- **Base Model**: ELECTRA base discriminator (`google/electra-base-discriminator`)

- **Pooling Layer**: Custom pooling layer supporting 'cls', 'mean', and 'max' pooling types.

- **Classifier**: Custom classifier with configurable hidden dimensions, number of layers, and dropout rate.

    - **Activation Function**: Custom SwishGLU activation function.



```

ElectraClassifier(

  (electra): ElectraModel(

    (embeddings): ElectraEmbeddings(

      (word_embeddings): Embedding(30522, 768, padding_idx=0)

      (position_embeddings): Embedding(512, 768)
      (token_type_embeddings): Embedding(2, 768)

      (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)

      (dropout): Dropout(p=0.1, inplace=False)

    )

    (encoder): ElectraEncoder(

      (layer): ModuleList(

        (0-11): 12 x ElectraLayer(

          (attention): ElectraAttention(

            (self): ElectraSelfAttention(

              (query): Linear(in_features=768, out_features=768, bias=True)

              (key): Linear(in_features=768, out_features=768, bias=True)

              (value): Linear(in_features=768, out_features=768, bias=True)

              (dropout): Dropout(p=0.1, inplace=False)

            )

            (output): ElectraSelfOutput(

              (dense): Linear(in_features=768, out_features=768, bias=True)

              (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)

              (dropout): Dropout(p=0.1, inplace=False)

            )

          )

          (intermediate): ElectraIntermediate(

            (dense): Linear(in_features=768, out_features=3072, bias=True)

            (intermediate_act_fn): GELUActivation()

          )

          (output): ElectraOutput(

            (dense): Linear(in_features=3072, out_features=768, bias=True)

            (LayerNorm): LayerNorm((768,), eps=1e-12, elementwise_affine=True)

            (dropout): Dropout(p=0.1, inplace=False)

          )

        )

      )

    )

  )

  (pooling): PoolingLayer()

  (classifier): Classifier(

    (layers): Sequential(

      (0): Linear(in_features=768, out_features=1024, bias=True)

      (1): SwishGLU(

        (projection): Linear(in_features=1024, out_features=2048, bias=True)

        (activation): SiLU()

      )

      (2): Dropout(p=0.3, inplace=False)

      (3): Linear(in_features=1024, out_features=1024, bias=True)

      (4): SwishGLU(

        (projection): Linear(in_features=1024, out_features=2048, bias=True)

        (activation): SiLU()

      )

      (5): Dropout(p=0.3, inplace=False)

      (6): Linear(in_features=1024, out_features=3, bias=True)

    )

  )

)

```



## Custom Model Components

### SwishGLU Activation Function

The SwishGLU activation function combines the Swish activation with a Gated Linear Unit (GLU). It enhances the model's ability to capture complex patterns in the data.

```python

class SwishGLU(nn.Module):

    def __init__(self, input_dim: int, output_dim: int):

        super(SwishGLU, self).__init__()

        self.projection = nn.Linear(input_dim, 2 * output_dim)

        self.activation = nn.SiLU()



    def forward(self, x):

        x_proj_gate = self.projection(x)

        projected, gate = x_proj_gate.tensor_split(2, dim=-1)

        return projected * self.activation(gate)

```

### PoolingLayer

The PoolingLayer class allows you to choose between different pooling strategies:

- `cls`: Uses the representation of the \[CLS\] token.
- `mean`: Calculates the mean of the token embeddings.
- `max`: Takes the maximum value across token embeddings.

**'mean'** pooling was used in the fine-tuned model.

```python

class PoolingLayer(nn.Module):

    def __init__(self, pooling_type='cls'):

        super().__init__()

        self.pooling_type = pooling_type



    def forward(self, last_hidden_state, attention_mask):

        if self.pooling_type == 'cls':

            return last_hidden_state[:, 0, :]

        elif self.pooling_type == 'mean':

            return (last_hidden_state * attention_mask.unsqueeze(-1)).sum(1) / attention_mask.sum(-1).unsqueeze(-1)

        elif self.pooling_type == 'max':

            return torch.max(last_hidden_state * attention_mask.unsqueeze(-1), dim=1)[0]

        else:

            raise ValueError(f"Unknown pooling method: {self.pooling_type}")

```

### Classifier

The Classifier class is a customizable feed-forward neural network used for the final classification.

The fine-tuned model had:

- `input_dim`: 768
- `num_layers`: 2
- `hidden_dim`: 1024
- `hidden_activation`: SwishGLU
- `dropout_rate`: 0.3
- `n_classes`: 3

```python

class Classifier(nn.Module):

    def __init__(self, input_dim, hidden_dim, hidden_activation, num_layers, n_classes, dropout_rate=0.0):

        super().__init__()

        layers = []

        layers.append(nn.Linear(input_dim, hidden_dim))

        layers.append(hidden_activation)

        if dropout_rate > 0:

            layers.append(nn.Dropout(dropout_rate))



        for _ in range(num_layers - 1):

            layers.append(nn.Linear(hidden_dim, hidden_dim))

            layers.append(hidden_activation)

            if dropout_rate > 0:

                layers.append(nn.Dropout(dropout_rate))



        layers.append(nn.Linear(hidden_dim, n_classes))

        self.layers = nn.Sequential(*layers)

```

## Model Configuration

The model's configuration (config.json) includes custom parameters:

- `hidden_dim`: Size of the hidden layers in the classifier.
- `hidden_activation`: Activation function used in the classifier ('SwishGLU').
- `num_layers`: Number of layers in the classifier.
- `dropout_rate`: Dropout rate used in the classifier.
- `pooling`: Pooling strategy used ('mean').

## Performance by Dataset

### Merged Dataset

```

Merged Dataset Classification Report



              precision    recall  f1-score   support



    negative   0.847081  0.777211  0.810643      2352

     neutral   0.704453  0.761072  0.731669      1829

    positive   0.828047  0.844615  0.836249      2349



    accuracy                       0.796937      6530

   macro avg   0.793194  0.794299  0.792854      6530

weighted avg   0.800285  0.796937  0.797734      6530



ROC AUC: 0.926344



Predicted  negative  neutral  positive

Actual                                

negative       1828      331       193

neutral         218     1392       219

positive        112      253      1984



Macro F1 Score: 0.79

```

### DynaSent Round 1

```

DynaSent Round 1 Classification Report



              precision    recall  f1-score   support



    negative   0.901222  0.737500  0.811182      1200

     neutral   0.745957  0.922500  0.824888      1200

    positive   0.850970  0.804167  0.826907      1200



    accuracy                       0.821389      3600

   macro avg   0.832716  0.821389  0.820992      3600

weighted avg   0.832716  0.821389  0.820992      3600



ROC AUC: 0.945131



Predicted  negative  neutral  positive

Actual                                

negative        885      201       114

neutral          38     1107        55

positive         59      176       965



Macro F1 Score: 0.82

```

### DynaSent Round 2

```

DynaSent Round 2 Classification Report



              precision    recall  f1-score   support



    negative   0.696154  0.754167  0.724000       240

     neutral   0.770408  0.629167  0.692661       240

    positive   0.704545  0.775000  0.738095       240



    accuracy                       0.719444       720

   macro avg   0.723702  0.719444  0.718252       720

weighted avg   0.723702  0.719444  0.718252       720



ROC AUC: 0.88842



Predicted  negative  neutral  positive

Actual                                

negative        181       26        33

neutral          44      151        45

positive         35       19       186



Macro F1 Score: 0.72

```

### Stanford Sentiment Treebank (SST-3)

```

SST-3 Classification Report



              precision    recall  f1-score   support



    negative   0.831878  0.835526  0.833698       912

     neutral   0.452703  0.344473  0.391241       389

    positive   0.834669  0.916392  0.873623       909



    accuracy                       0.782353      2210

   macro avg   0.706417  0.698797  0.699521      2210

weighted avg   0.766284  0.782353  0.772239      2210



ROC AUC: 0.885009



Predicted  negative  neutral  positive

Actual                                

negative        762      104        46

neutral         136      134       119

positive         18       58       833



Macro F1 Score: 0.70

```

## License

This model is licensed under the MIT License.

## Citation

If you use this model in your work, please consider citing it:

```bibtex

@misc{beno-2024-electra_base_classifier_sentiment,

  title={Electra Base Classifier for Sentiment Analysis},

  author={Jim Beno},

  year={2024},

  publisher={Hugging Face},

  howpublished={\url{https://huggingface.co/jbeno/electra-base-classifier-sentiment}},

}

```

## Contact

For questions or comments, please open an issue on the repository or contact [Jim Beno](https://huggingface.co/jbeno).

## Acknowledgments

- The [Hugging Face Transformers library](https://github.com/huggingface/transformers) for providing powerful tools for model development.
- The creators of the [ELECTRA model](https://arxiv.org/abs/2003.10555) for their foundational work.
- The authors of the datasets used: [Stanford Sentiment Treebank](https://huggingface.co/datasets/stanfordnlp/sst), [DynaSent](https://huggingface.co/datasets/dynabench/dynasent).
- [Stanford Engineering CGOE](https://cgoe.stanford.edu), [Chris Potts](https://stanford.edu/~cgpotts/), and the Course Facilitators of [XCS224U](https://online.stanford.edu/courses/xcs224u-natural-language-understanding)