render

Renders the chart as an anywidget that displays in Jupyter, JupyterLab, VS Code notebooks, and marimo.

from gofish import chart, spread, rect

chart(seafood, axes=True).flow(spread(by="lake", dir="x")).mark(
    rect(h="count")
).render(w=500, h=300)

Signature

ChartBuilder.render(w=800, h=600, axes=None, legend=None, padding=None, debug=False)

layer(...) and .layer(...) chains (LayerBuilder) and bare marks take the same options. They are the JS .render(container, options) options, in snake case.

Parameters

Parameter	Type	Default	Description
w	int	800	Width in pixels
h	int	600	Height in pixels
axes	bool | dict | None	None	Auto-generate axes, labels, and legends; same shape as chart(axes=...). Unset, the chart's own axes option decides.
legend	bool | None	None	Whether to draw the color-scale legend. Unset, the default (True) applies. A chart() option of the same name wins over this one.
padding	float | None	None	Extra pixels between the drawing and the SVG edge. Unset, the chart's own padding option (or the default) applies.
debug	bool	False	Whether to enable debug rendering

Returns a GoFishChartWidget.

Axes on the chart or on render

axes (and padding) can be passed to chart or to render, as in JS (chart(data, { axes: true }) or .render(container, { axes: true })). See chart for the full axes shape.

Automatic display

A ChartBuilder displays itself when it is the last expression in a notebook cell — no .render() call is required:

chart(seafood).flow(spread(by="lake", dir="x")).mark(rect(h="count"))

This is equivalent to calling .render() with its defaults. Call .render() explicitly when you want to set the size or other render options:

chart(seafood, axes=True).flow(spread(by="lake", dir="x")).mark(
    rect(h="count")
).render(w=500, h=300)

Inspecting the IR

.to_ir() returns the chart's JSON intermediate representation instead of rendering — useful for debugging or testing:

chart(seafood).flow(spread(by="lake", dir="x")).mark(rect(h="count")).to_ir()

Notes

• Rendering requires a notebook kernel — render() produces a widget. To get an SVG file or string, use save / to_svg.
• A chart must have a mark before it can be rendered.