line

Connects data points with a line. A line draws through a set of points, so it is most often paired with select() to trace a layout produced by another chart.

from gofish import Layer, chart, scatter, blank, select, line

Layer([
    chart(catch_locations)
        .flow(scatter(by="lake", x="x", y="y"))
        .mark(blank().name("points")),
    chart(select("points")).mark(line()),
]).render(w=500, h=300, axes=True)

Signature

line(stroke=None, strokeWidth=None, opacity=None, interpolation=None) -> Mark

Parameters

Parameter	Type	Description
stroke	str	Line color
strokeWidth	int	Line width in pixels
opacity	float	Opacity, 0–1
interpolation	str	Curve interpolation, e.g. "linear", "monotone"

Returns a Mark for use in .mark().

The line pattern

A line needs points to connect. The idiomatic recipe:

1. One chart positions invisible blank marks and names the layer with .name("points").
2. A second chart selects that layer — chart(select("points")) — and draws a line() through it.
3. Layer([...]) composes the two.

This separation lets the same positioned points back both a line and, say, circles drawn on top.

Examples

# Styled line
chart(select("points")).mark(line(stroke="black", strokeWidth=2))