opendatalab / ChartVerse-Coder

ChartVerse-Coder is a complexity-aware chart code generator that can autonomously synthesize diverse, high-complexity chart codes from scratch, developed as part of the opendatalab/ChartVerse project. For more details about our method, datasets, and full model series, please visit our Project Page .

Unlike prior template-based or seed-conditioned approaches, ChartVerse-Coder generates chart code via high-temperature sampling, enabling broad exploration of the long-tail chart distribution and producing diverse, realistic charts with high structural complexity.

🔥 Highlights

• Autonomous Synthesis : Generates diverse chart codes from scratch without templates or seed charts
• Complexity-Aware : Trained with RPE-guided filtering to master high-complexity visualizations
• High Diversity : Produces charts spanning 3D plots, hierarchical structures, multi-subplot layouts, and more
• Iterative Self-Enhancement : Progressively improves code quality through generation-filtering-retraining loops

🔬 Method Overview

Rollout Posterior Entropy (RPE)

We propose Rollout Posterior Entropy (RPE) to quantify intrinsic chart complexity via generative stability:

1. VLM Rollout : Given a chart, prompt a VLM to generate executable code 8 times with temperature 1.0
2. Feature Extraction : Extract CLIP embeddings from reconstructed images and compute Gram matrix
3. Spectral Entropy : Calculate entropy from normalized singular values

Key Insight : Simple charts yield consistent reconstructions (low RPE), while complex charts result in divergent outcomes (high RPE). We retain only samples with RPE ≥ 0.4 .

Training Pipeline

Stage 1: Difficulty-Filtered Cold Start

• Aggregate charts from existing datasets and filter by RPE ≥ 0.4
• Use Claude-4-Sonnet to infer source code for high-complexity charts
• Curate 60K high-quality seed samples

Stage 2: Iterative Self-Enhancement

• Generate 2M raw candidates via high-temperature sampling
• Apply tri-fold filtering:
  • ✅ Valid Execution
  • ✅ High Complexity (RPE ≥ 0.4)
  • ✅ Low Similarity to existing data (Cosine Sim ≤ 0.65)
• Retrain coder on expanded dataset
• Repeat for 2 iterations

Final Output : Generate 1M high-complexity chart code samples for downstream QA synthesis.

🏋️ Training Details

• Base Model : Qwen2.5-Coder-7B-Instruct
• Cold Start Data : 60K high-complexity samples
• Boost Data : 200K iteratively filtered samples
• Training : Full-parameter fine-tuning with LLaMA-Factory
• Learning Rate : 2.0 × 10⁻⁵
• Batch Size : 16
• Context Length : 4,096 tokens
• Epochs : 5
• Precision : BF16

📊 Synthesized Data Quality

Comparison with Existing Datasets

ChartVerse-Coder synthesizes charts with significantly higher complexity and diversity than all existing datasets.

Synthesized Chart Examples

Our synthesized charts demonstrate exceptional diversity:

• 3D Visualizations : Surface plots, 3D bar charts, scatter plots
• Hierarchical Structures : Treemaps, sunburst charts, dendrograms
• Statistical Plots : Violin plots, radar charts, box plots with annotations
• Multi-Subplot Layouts : Complex dashboards with mixed chart types
• Specialized Charts : Sankey diagrams, chord diagrams, heatmaps with clustering

🚀 Quick Start

from transformers import AutoModelForCausalLM, AutoTokenizer

# Load Model
model_path = "opendatalab/ChartVerse-Coder"
model = AutoModelForCausalLM.from_pretrained(
    model_path, torch_dtype="auto", device_map="auto"
)
tokenizer = AutoTokenizer.from_pretrained(model_path)

# System Prompt
prompt = """You are a Python visualization expert. Generate a random Python visualization code focusing on charts, tables, or diagrams.

Requirements:
- Choose any visualization type (chart, table, flowchart, diagram, etc.)
- Create sample data
- Use Python visualization library (matplotlib, graphviz, etc.)
- Make it visually appealing with proper labels, titles, and colors
- Include sufficient visual elements
- Carefully design the layout to avoid any overlapping text or elements
- Adjust figure size, margins, and spacing for optimal clarity
- Make it visually appealing with proper labels, titles, and colors

Output format: Only output the Python visualization code wrapped in ```python```
"""

# Generate Chart Code
messages = [
    {"role": "user", "content": prompt}
]

text = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
inputs = tokenizer(text, return_tensors="pt").to("cuda")

# High-temperature sampling for diversity
outputs = model.generate(
    **inputs,
    max_new_tokens=4096,
    temperature=1.0,
    top_p=0.95,
    top_k=20,
    do_sample=True
)

generated_code = tokenizer.decode(outputs[0], skip_special_tokens=True)
print(generated_code)

Execute Generated Code

import re
import matplotlib.pyplot as plt

# Extract code from response
code_match = re.search(r'```python\n(.*?)```', generated_code, re.DOTALL)
if code_match:
    code = code_match.group(1)
    exec(code)  # This will save the figure as 'image.png'

📖 Citation

@article{chartverse2026,
  title={ChartVerse: Scaling Chart Reasoning via Reliable Programmatic Synthesis from Scratch},
  author={Anonymous Authors},
  journal={Anonymous ACL Submission},
  year={2026}
}

📄 License

This model is released under the Apache 2.0 License.

🙏 Acknowledgements

• Base model: Qwen2.5-Coder-7B-Instruct
• Training framework: LLaMA-Factory
• Code inference: Claude-4-Sonnet for cold start data generation