EmCoder

Probabilistic Emotion Recognition & Uncertainty Quantification
28 Emotion multi-label Transformer classifier
Live Demo & API Service: Try EmCoder on Hugging Face Spaces

Unlike standard classifiers, EmCoder quantifies what it doesn't know using Monte Carlo Dropout, making it suitable for high-stakes AI pipelines.
EmCoder is optimized for MC Dropout inference and its architecture has no limit on maximum input length thanks to RoPE.

SOTA benchmark

Evaluation on the GoEmotions test split (macro avg metrics)

EmCoder achieves highly competitive Macro F1-score with its compact size (~35% smaller than RoBERTa-base and ~45% smaller than ModernBERT), while providing per-class epistemic uncertainty quantification.

Model	Precision	Recall	F1-Score	Params	F1/M
EmCoder	0.503	0.503	0.488	81.8M	0.0060
Google BERT (Original)	0.400	0.630	0.460	110M	0.0042
RoBERTa-base	0.575	0.396	0.450	125M	0.0036
ModernBERT-base	0.583	0.535	0.550	149M	0.0037

How to use

1. Setup & Tokenization

EmCoder uses the ModernBERT tokenizer for correct token-to-embedding mapping.
Ensure you allow remote code execution since it's a custom architecture.

import torch
from transformers import AutoModelForSequenceClassification, AutoTokenizer

repo_id = "yezdata/EmCoder"

# Load the same tokenizer used during training
tokenizer = AutoTokenizer.from_pretrained("answerdotai/ModernBERT-base")

# Initialize with same config as training
model = AutoModelForSequenceClassification.from_pretrained(repo_id, trust_remote_code=True)

2. Bayesian inference

To obtain probabilistic outputs and uncertainty metrics, use the mc_forward method:

# Perform 50 stochastic passes
N_SAMPLES = 50
MAX_BATCH_SIZE = 10 # optional sub-batching of N_SAMPLES

inputs = tokenizer("I am so happy you are here!", return_tensors="pt")

model.eval()
with torch.no_grad():
    # Automatically keeps Dropout active, even when in model.eval
    outputs = model.mc_forward(
        **inputs,
        n_samples=N_SAMPLES,
        max_batch_size=MAX_BATCH_SIZE
    )

# Bayesian Post-processing
mc_logits = outputs.logits
all_probs = torch.sigmoid(mc_logits) # (n_samples, B, 28)

mean_probs = all_probs.mean(dim=0) # Mean Predicted Probability
# base std estimation of Epistemic Uncertainty
uncertainty = all_probs.std(dim=0)

# Formatted Output
m_probs = mean_probs.squeeze(0)
u_vals = uncertainty.squeeze(0)

print(f"{'Emotion':<15} | {'Prob':<10} | {'Uncertainty':<10}")
print("-" * 40)

sorted_indices = torch.argsort(m_probs, descending=True)

for idx in sorted_indices:
    prob, unc = m_probs[idx].item(), u_vals[idx].item()
    label = model.config.id2label[idx.item()]
    
    if prob > 0.05: # Print only emotions with prob > 5%
        print(f"{label:<15} | {prob:>8.2%} | ±{unc:>8.4f}")

Model Architecture

Optimization

The model is trained using a Weighted Binary Cross Entropy loss
Where weights w are calculated using a logarithmic class-balancing scale to handle extreme label imbalance:

$$w_c=\max (0.1,\min (20,1+\ln \left(\frac{N_{neg,c}+ϵ}{N_{pos,c}+ϵ}\right)))w\_\{c\}\; =\; \backslash max\backslash left(\; 0.1,\; \backslash min\backslash left(\; 20,\; 1\; +\; \backslash ln\; \backslash left(\; \backslash frac\{N\_\{neg,c\}\; +\; \backslash epsilon\}\{N\_\{pos,c\}\; +\; \backslash epsilon\}\; \backslash right)\; \backslash right)\; \backslash right)$$

Performance on test set

Using thresholds.json optimization of probabilty thresholds for binarizing predictions (from val set)

	precision	recall	f1-score	support
micro avg	0.524	0.635	0.574	6329
macro avg	0.503	0.503	0.488	6329
weighted avg	0.537	0.635	0.573	6329
samples avg	0.562	0.661	0.584	6329
----------------	-----------	----------	----------	-----------
admiration	0.642	0.681	0.661	504
amusement	0.731	0.898	0.806	264
anger	0.491	0.434	0.461	198
annoyance	0.352	0.316	0.333	320
approval	0.273	0.501	0.354	351
caring	0.271	0.415	0.327	135
confusion	0.377	0.392	0.385	153
curiosity	0.496	0.648	0.562	284
desire	0.525	0.373	0.437	83
disappointment	0.272	0.305	0.288	151
disapproval	0.333	0.461	0.387	267
disgust	0.422	0.528	0.469	123
embarrassment	0.545	0.324	0.407	37
excitement	0.467	0.340	0.393	103
fear	0.565	0.667	0.612	78
gratitude	0.946	0.889	0.917	352
grief	0.667	0.333	0.444	6
joy	0.603	0.584	0.593	161
love	0.809	0.782	0.795	238
nervousness	0.500	0.174	0.258	23
optimism	0.614	0.478	0.538	186
pride	0.583	0.438	0.500	16
realization	0.270	0.214	0.238	145
relief	0.118	0.364	0.178	11
remorse	0.551	0.768	0.642	56
sadness	0.576	0.462	0.512	156
surprise	0.511	0.482	0.496	141
neutral	0.564	0.838	0.674	1787

Entropy-based Uncertainty Decomposition

EmCoder computes probabilistic uncertainty using Information Theory metrics over N stochastic forward passes

Demonstration of model uncertainty utilization
To validate uncertainty quantification, reject the top X% most uncertain (epistemic) classifications. The model's Macro F1 jumps from 0.488 to above 0.70, proving that the model's self-reported uncertainty is highly correlated with its actual error rate

Uncertainty quantification on GoEmotions test set for selected emotions

• admiration: medium appereance
• fear: minority representation
• neutral: the most samples

Admiration	Fear

Neutral

Emotion uncertainty distribution

Epistemic	Aleatoric

Co-occurrence Confusion Matrix (normalized to Recall %)

Workflow

Concrete Dropout Experiment

An experimental branch of EmCoder integrated Concrete Dropout (Gal et al., 2017) to dynamically learn optimal dropout probabilities. While this marginally sharpened the isolation of extreme edge-cases (yielding a slightly steeper first part on the F1-Rejection curve with an optimized p=0.15), the resulting heavier regularization constrained the capacity of compact EmCoder. This caused a slight degradation in standard macro metrics. Consequently, the production EmCoder model utilizes a fixed p=0.1 to maintain optimal encoder-classifier synergy.

Note

Note that this model was trained on GoEmotions dataset (social networks domain) and it may not generalize well to other domains.

Citation

If you use this model, please cite it as follows:

@misc{jez2026emcoder,
  author = {Václav Jež},
  title = {EmCoder},
  year = {2026},
  publisher = {Hugging Face},
  howpublished = {\url{https://huggingface.co/yezdata/EmCoder}},
  version = {1.0.0}
}