py2mermaid 0.2.0

A Python helper library to create Mermaid.js diagrams

Updated README.md

# py2mermaid

py2mermaid is a Python library that makes it easy to generate [Mermaid.js](https://mermaid.js.org/) diagrams directly from Python.

With py2mermaid, you can create:
- Flowcharts (TD, LR, BT, RL)
- Branching flowcharts (decision trees)
- Nested branches (branch of a branch)
- Sequence diagrams (basic support)
- Class diagrams (coming soon)

Mermaid.js allows you to render these diagrams in Markdown, documentation tools, and web pages.

---

## 📦 Installation

### From PyPI
```bash
pip install py2mermaid

From GitHub

pip install git+https://github.com/yourusername/py2mermaid.git

---

📂 What is .mmd?

A .mmd file is a plain text file containing Mermaid diagram syntax. Example: flowchart TD followed by your nodes and edges.

Example example_chart.mmd:

flowchart TD
A[Start]
B[Process]
C[End]
A --> B
B --> C

You can:

• Open it in Mermaid Live Editor
• Use it in GitHub Markdown
• Embed it in static site generators (MkDocs, Docusaurus, etc.)
• Preview it in editors like VS Code (with Mermaid plugin)

---

🚀 Quick Start

from py2mermaid.chart import MermaidChart

chart = MermaidChart(chart_type="flowchart", direction="TD")
chart.add_node("A", "Start")
chart.add_node("B", "Process")
chart.add_node("C", "End")
chart.add_edge("A", "B", "step 1")
chart.add_edge("B", "C", "step 2")

print(chart.render())

Output Mermaid code:

flowchart TD
A[Start]
B[Process]
C[End]
A -->|step 1| B
B -->|step 2| C

flowchart TD   
A[Start]       
B[Process]     
C[End]
A -->|step 1| B
B -->|step 2| C

---

🛠 Using Utility Functions

The utils.py file includes:

• save_chart(chart, filename) → Saves Mermaid code to .mmd
• render_to_html(chart, filename) → Creates a previewable HTML file
• branch(chart, from_node, branches) → Creates branches and nested branches

---

1️⃣ Save a Chart as .mmd

from py2mermaid.chart import MermaidChart
from py2mermaid.utils import save_chart

chart = MermaidChart("flowchart", "LR")
chart.add_node("A", "Start")
chart.add_node("B", "Do Work")
chart.add_edge("A", "B")

save_chart(chart, "my_chart")  # Saves as my_chart.mmd

---

2️⃣ Render to HTML for Preview

from py2mermaid.utils import render_to_html

render_to_html(chart, "my_chart")  # Saves as my_chart.html
# Open in browser to view

---

3️⃣ Branching Flowchart (Decision Tree)

from py2mermaid.chart import MermaidChart
from py2mermaid.utils import branch

chart = MermaidChart("flowchart", "TD")
chart.add_node("A", "Start")

branch(chart, "A", [
    ("B", "Option 1"),
    ("C", "Option 2")
])

print(chart.render())

Output:

flowchart TD
A[Start]
B[Option 1]
C[Option 2]
A --> B
A --> C

flowchart TD
A[Start]
B[Option 1]
C[Option 2]
A --> B
A --> C

---

4️⃣ Nested Branches (Branch of a Branch)

chart = MermaidChart("flowchart", "TD")
chart.add_node("A", "Start")

branch(chart, "A", [
    ("B", "Path 1", [
        ("B1", "Path 1A"),
        ("B2", "Path 1B")
    ]),
    ("C", "Path 2")
])

print(chart.render())

Output:

flowchart TD
A[Start]
B[Path 1]
B1[Path 1A]
B2[Path 1B]
C[Path 2]
A --> B
B --> B1
B --> B2
A --> C

---

💡 Tips

• py2mermaid generates code — rendering is done by Mermaid.js in browsers or Markdown processors.
• Save .mmd files to reuse diagrams in docs.
• Use render_to_html() for instant browser preview.

---

📜 License

This project is licensed under the MIT License.

---

🤝 Contributing

1. Fork the repo
2. Create a new branch: git checkout -b feature-name
3. Make changes and commit: git commit -m 'Added new feature'
4. Push to branch: git push origin feature-name
5. Open a Pull Request

---

I’ve now included:
- `.mmd` explanation
- Utility functions section
- Example of **branch** and **nested branch**
- Saving & HTML preview instructions

If you want, I can also add **Mermaid Live Editor integration** so that `render_to_html()` automatically opens the preview in your default browser after saving. That would make it even smoother for testing.  

Do you want me to add that?