Plots in the terminal (with sixel)

[Alexander-Barth]

I just came across “sixel” which allows to show graphics in the terminal (while reading this GitHub - csdvrx/sixel-gnuplot: GNUplot with sixel support )

Unfortunately, gnome-terminal does not support this (Bug 729204 – sixel support), but xterm (run as xterm -ti vt340) does.

In fact it does not take much to use this with julia and PyPlot (or any other plotting package), just the convert tool from ImageMagic.

I started Julia with unset DISPLAY (on Linux)

using PyPlot
plt.style.use("dark_background")
function show()
   fname = tempname() * ".png";
   savefig(fname)
   run(`convert $fname -geometry 800x480  sixel:-`)
   return nothing
end
x = 1:0.1:10;
pcolor(sin.(x) * sin.(x)');
show()

Off-topic, but also useful is lsix: “ls” for images (GitHub - hackerb9/lsix: Like "ls", but for images. Shows thumbnails in terminal using sixel graphics.)

[tshort]

You could also try the unregistered https://github.com/tshort/SixelTerm.jl. It uses ImageMagick.

[Alexander-Barth]

SixelTerm.jl is really nice! Thanks for sharing! It is quite impressive what you can do with 30 lines of code in SixelTerm.jl.

[jheinen]

GR has builtin sixel support:

using GR
inline("iterm")
contourf(peaks())

Could also be integrated into Plots gr() backend - just let me know …

[Alexander-Barth]

It could also be useful to overload the display function to make a plot for long vector and a heatmap for large matrices. I think I will use the feature at lot more!

ENV["GKSwstype"] = "nul"    # needed for the GR backend on headless servers
using Plots
using SixelTerm
using NCDatasets

function Base.display(x::Matrix{T}) where T <: Union{Number,Union{Missing,Number}}
    if length(x) < 300
        invoke(display, Tuple{AbstractMatrix}, x)
    else
        display(heatmap(coalesce.(x,NaN)', color=:lightrainbow))
    end
end


ds = Dataset("/home/abarth/Data/DivaData/Global/gebco_30sec_16.nc");
bathymetry = ds["bat"][:,:] # returns a Array{Union{Missing, Float32},2}

[jheinen]

… no need to overload display in GR:

[joa-quim]

Not in the REPL but I still prefer

using GMT
grdimage("@earth_relief_05m.grd", proj=:Winkel, fmt=:png, show=true)

[simonschoelly]

But if I see that correctly, this means, that GR.jl can only plot using terminals that are hard coded in GR.jl, right`

[Tamas_Papp]

I ran into some pages in Japanese when looking for the details of the sixel generation algorithm so I cannot judge how complex it is, but I am wondering if it would make sense to have a native Julia implementation. It would have obvious advantages for all packages using this functionality, and could also serve as a nice reference.

[jheinen]

GR.jl is only a wrapper for the GR framework. Any software that uses GR.jl can produce sixel graphics. It’s just about converting an internally rendered image to sixels …

Thus, it can be used from Julia, Python C, or whatever.

[mbaz]

The latest release of Gaston also supports sixel:

I had had experimental support for a while, but this thread motivated me to finish it up. Also, since gnuplot has native sixel support, no external libraries or converters are needed.

[dpo]

This really seems like the minimum time to first plot after UnicodePlots! GR doesn’t appear to have a spy() for sparse matrices. I put this together quickly to plot sparsity patterns in iTerm2 and it’s great:

function spy(A::AbstractSparseMatrix)
  nrows, ncols = size(A)
  rows, cols, vals = findnz(A)
  avals = abs.(vals)
  scatter(cols, rows, 50 * ones(length(rows)), 255 * avals ./ maximum(avals), xlim=(1, ncols), ylim=(1, nrows), yflip=true)
end

This could be a great alias for show() for sparse matrices in terminals that support it.
However, I’m not finding a convenient reference for keyword arguments accepted by GR. How do I

• adjust the aspect ratio to match the matrix?
• choose my own x and y ticks?
• remove the background grid?

[chakravala]

I would like to be able to set an environment variable that makes the sixel terminal display default for all plotting packages, so that when I load any plotting package I don’t need to configure.

[mbaz]

In the meantime, remember that you can add configuration commands to your ~/.juliarc file.

[chakravala]

That would require loading a plotting package each time I launch Julia, which I definitely don’t want in my startup file.

Currently, enabling sixel requires setting an option after loading the package.

The point of having an environment variable is to pre-set the option before any plotting package is loaded, so that I can choose to load plotting whenever I need it, without worrying about enabling sixel.

[chakravala]

What’s an environment variable plotting could agree on? ENV["SIXEL"] perhaps?

[mbaz]

You could add this function to your .juliarc:

function plot_with_gaston()
    @eval using Gaston
    @eval set(terminal="sixelgd")
end

and just call it when you’re ready to plot.

[isentropic]

Although this is late, would you please let me how to achieve this with plots? I’d like to get this to work in Plots

[jheinen]

env GKSwstype=iterm julia
...
julia> using Plots
julia> plot(randn(10))

For any reason, in Plots.jl the resulting plot is not HiDPI, but at least it works …

[piechologist]

This is an old thread but if some desperate soul is still looking for a solution I want to share my accidental discovery:

How to plot inside iTerm on macOS

This produces sharp plots even on Retina displays. Adjust the size and scaling to your liking.

using Plots
theme(:dark)  # for dark terminal backgrounds
default(display_type=:inline, size=(1500,800), thickness_scaling=1.5)
plot(rand(20))

(Minor) caveats: - The GKS QT terminal starts in the background (it doesn't open a window). - You can even ssh into a headless remote machine and initiate the plot there. Some QT related error messages do appear though.

Set the the environment variable GKSwstype=nul before starting julia to suppress the launching of gksqt.

You can even ssh into a headless remote machine and initiate the plot there.

EDIT: How to avoid GKSQT. Thanks to Plots in the terminal (with sixel) - #31 by jheinen.