streamlit-adjustable-columns 0.2.0

A Streamlit custom component for creating columns with adjustable widths

🎯 Streamlit Adjustable Columns

Version: 0.2.0

Create resizable columns in Streamlit! This component provides st.columns functionality with draggable resize handles that allow users to adjust column widths dynamically.

✨ Features

• 🎯 Drop-in Replacement: Works exactly like st.columns with the same API
• 🖱️ Resizable Boundaries: Drag handles between columns to adjust widths
• 💾 Persistent State: Column widths persist across app reruns
• 🎨 Theme Integration: Automatically matches your Streamlit theme
• 📱 Responsive: Works on desktop and mobile devices
• ⚙️ Full Compatibility: Supports all st.columns parameters (gap, alignment, border)
• 🔒 Minimum Width: 6% minimum width constraint prevents unusably narrow columns
• 📊 Width Tracking: Optional return_widths parameter for dynamic layouts

🚀 Quick Start

Installation

pip install streamlit-adjustable-columns

Note: Packages installed from PyPI already include the compiled frontend so no additional tools are required. If you install from a source checkout (e.g. GitHub), Node.js and npm are needed to build the frontend assets.

Basic Usage

import streamlit as st
from streamlit_adjustable_columns import adjustable_columns

# Use exactly like st.columns - but with resize handles!
col1, col2, col3 = adjustable_columns(3, labels=["📊 Charts", "📋 Data", "⚙️ Settings"])

with col1:
    st.metric("Sales", "$1,234", "12%")
    
col2.write("This column can be resized!")
col3.button("Settings")

✅ Success Indicators

You know it's working when you see:

• ✅ Column headers with drag handles between them
• ✅ Ability to drag column separators to resize
• ✅ Column widths persist when you interact with other elements
• ✅ Responsive behavior on different screen sizes

📖 API Reference

adjustable_columns(spec, *, gap="small", vertical_alignment="top", border=False, labels=None, return_widths=False, key=None)

Creates resizable columns with draggable boundaries.

Parameters

• spec (int or list): Number of columns or width ratios
  • 3 → Three equal columns
  • [2, 1] → Two columns with 2:1 ratio
• gap (str): Space between columns - "small", "medium", or "large"
• vertical_alignment (str): Content alignment - "top", "center", or "bottom"
• border (bool): Show borders around columns
• labels (list): Custom labels shown in resize handles
• return_widths (bool): Return width information along with columns
• key (str): Unique component key (recommended for multiple instances)

Returns

• Default: List of column containers (same as st.columns)
• With return_widths=True: Dict with {'columns': [...], 'widths': [...]}

🎮 How to Resize

1. Look for resize handles above each set of adjustable columns
2. Hover over the boundaries between column areas - you'll see resize cursors
3. Click and drag the handles to adjust column widths
4. Release to apply changes - they persist across app reruns!

📚 Examples

Dashboard Layout

# Create a dashboard with resizable main content and sidebar
main, sidebar = adjustable_columns([4, 1], labels=["📊 Dashboard", "⚙️ Controls"])

with main:
    st.subheader("Analytics Overview")
    col1, col2 = st.columns(2)
    col1.metric("Revenue", "$45,231", "12%")
    col2.metric("Users", "1,429", "3%")
    st.line_chart(data)

with sidebar:
    st.selectbox("Time Period", ["1D", "1W", "1M"])
    st.checkbox("Show Trends")
    st.button("Refresh Data")

Width Tracking

# Track column widths for dynamic layouts
result = adjustable_columns([2, 1], labels=["Content", "Sidebar"], return_widths=True)
content, sidebar = result['columns']
current_widths = result['widths']

st.info(f"Current ratios: {[f'{w:.1f}' for w in current_widths]}")

with content:
    st.write("Main content area")
    
with sidebar:
    st.write("Adjustable sidebar")

Multiple Column Sets

# Each set of columns needs a unique key
cols1 = adjustable_columns(3, labels=["A", "B", "C"], key="top")
cols2 = adjustable_columns([1, 2], labels=["Left", "Right"], key="bottom")

# First row
cols1[0].metric("Metric 1", "100")
cols1[1].metric("Metric 2", "200") 
cols1[2].metric("Metric 3", "300")

# Second row  
cols2[0].button("Action")
cols2[1].write("Content area")

All Parameters

columns = adjustable_columns(
    spec=[3, 2, 1],                    # Custom width ratios
    gap="large",                       # Large spacing
    vertical_alignment="center",       # Center-align content
    border=True,                       # Show column borders
    labels=["📊 Charts", "📋 Data", "⚙️ Tools"],  # Custom labels
    return_widths=True,               # Get width info
    key="advanced_example"            # Unique identifier
)

cols = columns['columns']
widths = columns['widths']

🎨 Customization

Column Labels

Customize the labels shown in resize handles:

cols = adjustable_columns(
    3, 
    labels=["📈 Analytics", "🛠️ Tools", "📱 Mobile"]
)

Responsive Layouts

Use width information for responsive behavior:

result = adjustable_columns([2, 1], return_widths=True)
main_col, side_col = result['columns']
widths = result['widths']

# Adapt content based on current column width
if widths[0] > 3:  # Main column is wide
    main_col.plotly_chart(fig, use_container_width=True)
else:  # Main column is narrow
    main_col.write("Chart too narrow - expand column to view")

🔧 Development

Prerequisites

• Python 3.9+
• Node.js 18+
• npm or yarn
• Git

Setup

# Clone the repository
git clone https://github.com/danieljannai/streamlit-adjustable-columns
cd streamlit-adjustable-columns

# Create virtual environment
python3 -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# Install in development mode
make install-dev

# Or manually:
pip install -e ".[dev]"
cd streamlit_adjustable_columns/frontend
npm install
cd ../..

Development Workflow

# Terminal 1: Start frontend development server
make frontend-dev  # Or: cd streamlit_adjustable_columns/frontend && npm start

# Terminal 2: Run the demo (make sure venv is activated)
source venv/bin/activate
streamlit run example.py

What You'll See

1. Frontend Dev Server: http://localhost:3001

   • This serves the interactive column resizer component

2. Streamlit App: http://localhost:8501

   • Your main app with the adjustable columns

Testing

The project includes comprehensive tests using pytest and Playwright:

# Run all tests
make test

# Run only unit tests
make test-unit

# Run only E2E tests  
make test-e2e

# Run with coverage
pytest --cov=streamlit_adjustable_columns

Code Quality

# Format code
make format

# Check linting
make lint

# Run full check (format + lint + test)
make format && make lint && make test

Building and Publishing

# Build the package
make build

# Upload to PyPI (requires credentials)
make upload

🐛 Troubleshooting

Component shows "Loading..." forever

• Make sure the frontend dev server is running on port 3001
• Check that _RELEASE = False in streamlit_adjustable_columns/__init__.py

"Module not found" error

• Make sure your virtual environment is activated: source venv/bin/activate
• Reinstall dependencies: make install-dev

Frontend won't start

• Make sure Node.js and npm are installed
• Delete node_modules and run npm install again

Port conflicts

• If port 3001 or 8501 are busy, kill other processes or change ports in the configuration

🧪 Test Coverage

The project includes comprehensive test coverage:

• Unit Tests: Test core functionality, parameter handling, and state management
• Integration Tests: Test component behavior with Streamlit integration
• E2E Tests: Test user interactions, resize functionality, and visual elements
• Cross-browser Testing: Firefox and Chromium support via Playwright

Test files are organized in the tests/ directory:

• tests/test_unit.py - Unit tests for Python code
• tests/test_integration.py - Integration tests
• tests/test_*.py - E2E tests for specific features
• tests/streamlit_apps/ - Test Streamlit applications

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request. This is a brief overview of how to contribute:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Install development dependencies (make install-dev)
4. Make your changes and add tests
5. Run the test suite (make test)
6. Format your code (make format)
7. Commit your changes (git commit -m 'Add amazing feature')
8. Push to the branch (git push origin feature/amazing-feature)
9. Open a Pull Request

For detailed contributing guidelines, development setup, testing procedures, and release processes, please see CONTRIBUTING.md.

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Built with Streamlit
• Inspired by the need for flexible column layouts in Streamlit applications
• Developed with great assistance from Cursor AI coding assistant

👨‍💻 Author

Daniel Jannai Epstein

• GitHub: @danieljannai
• Created this component to enhance Streamlit's column functionality

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Made with ❤️ for the Streamlit community