Pygal

3.1.0 · active · verified Mon Apr 13

Pygal is an open-source Python library for creating dynamic and interactive SVG (Scalar Vector Graphics) charts. It is known for its ease of use, allowing developers to generate high-quality, scalable visualizations with minimal code. Pygal is currently at version 3.1.0 and maintains an active development and release cadence, with recent updates focusing on fixes and minor enhancements.

Warnings

gotcha When embedding Pygal SVGs directly into HTML, custom fonts defined in styles might not apply correctly. The browser might not fetch external stylesheets linked within the SVG if it's not embedded via an `<embed>` or `<iframe>` tag.
Fix: Embed the SVG using `<embed type="image/svg+xml" src="your_chart.svg">` or render the chart directly into a Flask/Django response, which typically handles embedding correctly. Alternatively, manually add the font stylesheet to your main HTML file.
gotcha Charts rendered in environments like Jupyter Notebooks might display raw SVG/XML metadata instead of the visual chart. This is because the notebook environment might not automatically interpret raw SVG strings as renderable content.
Fix: Use `chart.render_data_uri()` to get a base64 encoded URI, which can then be displayed in Jupyter using `IPython.display.HTML`. For file output, use `render_to_file()` and open the `.svg` file in a web browser. For interactive display, `render_in_browser()` (requires `lxml`) can be used, but this will open a new browser tab.
breaking Pygal 3.0.0 removed the `Iterable` import from `collections` (which was deprecated in Python 3.8 and removed in Python 3.10) and changed internal dependencies like `pytest` attributes and `pkg_resources` usage. Code relying on older Python versions (pre-3.8) or specific `pytest` internals might encounter issues.
Fix: Ensure you are using Python 3.8 or newer. Update your development environment to use recent versions of `pytest` if you are running tests against Pygal's internals. Migrate any custom code that might have indirectly relied on these deprecated Python features or library internals.
gotcha Rendering PNG output requires the `cairosvg` library. If `cairosvg` is not installed, calls to `render_to_png()` will raise an error.
Fix: Install `cairosvg` separately (`pip install cairosvg`) or install Pygal with the `[all]` extra: `pip install "pygal[all]"`.

Install

pip install pygal Install stable version
pip install "pygal[all]" Install with all optional dependencies

Imports

Bar
```
import pygal
chart = pygal.Bar()
```
While 'from pygal import Bar' works, the official documentation and common examples prefer importing 'pygal' and accessing chart types as attributes (e.g., pygal.Bar()). This aligns with the library's design for easily creating different chart types.
Style
```
from pygal.style import Style
```

Quickstart

This quickstart demonstrates how to create a simple bar chart with two data series and render it to an SVG file. It also shows the (commented out) option to render directly in a web browser, which requires the `lxml` optional dependency.

import pygal

# Create a Bar chart object
bar_chart = pygal.Bar()

# Add data series
bar_chart.add('Fibonacci', [0, 1, 1, 2, 3, 5, 8, 13, 21, 34])
bar_chart.add('Prime', [2, 3, 5, 7, 11, 13, 17, 19, 23, 29])

# Render the chart to an SVG file
bar_chart.render_to_file('bar_chart.svg')

# To display in a browser (requires lxml installed)
# bar_chart.render_in_browser()

print("Chart rendered to bar_chart.svg")

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