Getting started

Install

go get github.com/go-plot/plot@v0.1.0

Go 1.27.2 or later. Nothing else: no Python, no C library, no font to install. The fonts (DejaVu Sans for text, STIX Two Math for TeX) are compiled in.

A first figure

This is the example of go-plot’s README. It plots a sine as a line, then the same points as markers, labels the x axis with some TeX, adds a legend, and writes a PNG to standard output:

package main

import (
	"math"
	"os"

	"github.com/go-plot/plot"
)

func main() {
	x := make([]float64, 200)
	y := make([]float64, 200)
	for i := range x {
		x[i] = float64(i) / 20
		y[i] = math.Sin(x[i])
	}
	fig, axs := plot.Subplots(1, 1)
	ax := axs[0][0]
	ax.Plot(x, y, plot.Label(`$\sin t$`))
	ax.Plot(x, y, plot.Marker("o"), plot.LineStyle("None"), plot.MarkerSize(2))
	ax.SetXLabel(`time $t$ (s)`)
	ax.Legend()
	fig.SavePNG(os.Stdout)
}

go run . > sine.png

The same figure, saved with SaveSVG instead:

package main

import (
	"math"

	"github.com/go-plot/plot"
)

func init() { register("quickstart", quickstart) }

// The README's example, with SaveSVG in place of SavePNG.
func quickstart() *plot.Figure {
	x := make([]float64, 200)
	y := make([]float64, 200)
	for i := range x {
		x[i] = float64(i) / 20
		y[i] = math.Sin(x[i])
	}
	fig, axs := plot.Subplots(1, 1)
	ax := axs[0][0]
	ax.Plot(x, y, plot.Label(`$\sin t$`))
	ax.Plot(x, y, plot.Marker("o"), plot.LineStyle("None"), plot.MarkerSize(2))
	ax.SetXLabel(`time $t$ (s)`)
	ax.Legend()
	return fig
}

Read it as matplotlib:

The figure is matplotlib’s default: 6.4 × 4.8 inches at 100 dpi, so 640 × 480 pixels, with the tab10 colour cycle (the line is C0, the markers C1). plot.FigSize(w, h) and plot.DPI(d) change it:

fig, axs := plot.Subplots(2, 2, plot.FigSize(8, 6), plot.DPI(150))

Data

Data arguments take []float64, []float32, []int, []int32, []int64, a scalar, or a *ndarray.Array of any of go-ndarray’s dtypes. A type that cannot be plotted, or x and y of different lengths, panics: both are programming errors, as an index out of range is. See the API.

In a notebook

fig.Display() returns the figure in every format a notebook front end may show, keyed by MIME type: image/svg+xml and image/png. It is the display contract of the go-notebook kernel, so a cell whose last expression is a figure shows it; it is the notebook’s plt.show().

Next

• The API: the object model and why it has this shape.
• Plot types: every plot type, with the code that drew it.