export (SVG)

Save a chart to an SVG file. save() infers the format from the file extension; to_svg() returns the markup as a string. These sit alongside render.

from gofish import chart, spread, rect

# Last expression in a cell → displays and writes "seafood.svg".
chart(seafood, axes=True).flow(spread(by="lake", dir="x")).mark(
    rect(h="count")
).save("seafood.svg", w=500, h=300)

How it works

The SVG is produced by the notebook front-end, not the Python kernel, so export uses the same widget bridge as rendering:

• chart(...).save(path, ...) returns a widget that writes the file once it renders. Make it the last expression in a cell (or otherwise display it) so the render — and therefore the write — happen.
• After a widget has displayed, widget.to_svg() returns the markup and widget.svg exposes it as a property.

Because the write waits for the front-end to render, it completes asynchronously — shortly after the cell with the live widget runs. Truly synchronous, headless export (works in plain .py scripts / CI) is tracked in #577.

Signature

ChartBuilder.save(path, w=800, h=600, debug=False)   # returns a widget

GoFishChartWidget.save(path)        # write now (or defer until rendered)
GoFishChartWidget.to_svg() -> str   # markup; errors if not yet rendered
GoFishChartWidget.svg               # markup or None

Parameters

Parameter	Type	Default	Description
path	str	—	Output path. Format inferred from the extension (.svg).
w	int	800	Chart width in pixels
h	int	600	Chart height in pixels

Axes are a chart option

axes (and padding) are passed to chart, not save — mirroring render.

Working with the widget directly

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

# In a later cell, after it has rendered:
svg = w.to_svg()
w.save("seafood.svg")

Notes

• Only .svg is supported today; PNG and HTML are tracked in #578.
• Fonts are referenced, not embedded — a viewer without those fonts sees fallback fonts. Self-contained output (embedded/outlined fonts) is tracked in #578.
• Calling save() without ever displaying the widget writes nothing — the front-end must render to produce the SVG.