CpPGFplots :: simple yet beautiful plotting in C++

CpPGFplots is a library that aims to make plotting: consistent and easy in C++. It uses pgfplots backend to produce images, wrapping it’s syntax with a powerful programming language and choosing defaults that produce good-looking graphs as frequently as possible (and tries to be smart about it when possible). It’s also developed with Emacs’ org mode in mind and tries to make embedding plots there as easy as possible (in fact, look at orgmode-showcase.org file and see for yourself).

I mainly developed it for personal use, so beware bugs, inconsistencies you may encounter.

Showcase

To plot a simple $cos(x)$ you just need to use function and specify range. Library will automatically determine necessary amount of samples and output latex code you can embed in your article (only requirement for your latex is to use pgfplots, but that’s obvious).

plotting_plane plane = function(cos(x), { -15, 15 });

plane.generate_image("figures/graph-0.png");

A little more elaborate example showcases multiple graphs on single plane, labels and legend:

auto plot_sin = function(sin(x),    { -15, 15 });
plot_sin.name = "$\\sin \\left ( x \\right )$";

auto plot_cos = function(cos(10*x), { -15, 15 });
plot_cos.name = "$\\cos \\left ( 10 x \\right )$";

plotting_plane plane = plot_sin + plot_cos;
plane.name = "Showcase of multiple graphs on single plane";

auto &[x_axis, y_axis] = plane.axes;
x_axis.label = "$x$";
y_axis.label = "$f(x)$";

plane.generate_image("figures/graph-1.png");

There are, of course, a large number of parameters you can tweak to get different results, let’s, for example, see sampled points in on this graph (there are so much, it just looks like a thicker plot):

auto parabola = function(x*x, { - 20, 20 });
parabola.mark_size = 0.5; // Enable marks

plotting_plane plane("This is a parabola with sample points ($x^2$)");
plane + parabola;

plane.generate_image("figures/graph-2.png");

This graph showcases plotting from points and a new interpolation mode (before that we only built plots with segments), here it’s interpolated smoothly, hence the name:

auto current_plot = points(
    { -1,  2 },
    {  3, 11 },
    {  5,  9 },
    {  6,  8 },
    {  9,  9 }
);

current_plot.interpolate = SMOOTH;

plotting_plane plane = current_plot;
plane.generate_image("figures/graph-3.png");

And, having all of C++ around, you can do lots of things you wouldn’t be able to do in pure pgfplots (or, it would be harder, at lease). Let’s, for example, build a progression of fibonacci numbers:

std::vector<vec2> points;

auto fib = [](auto &&recursive, int x) {
    if (x == 0 || x == 1)
        return 1;

    return recursive(recursive, x - 1) + recursive(recursive, x - 2);
};

for (int i = 0; i < 30; ++ i)
    points.emplace_back(i, fib(fib, i));

plot current_plot { points };
current_plot.interpolate = NONE;

plotting_plane plane = current_plot;
plane.generate_image("figures/graph-4.png");

Installation and Building

You need to have glm library install system-wide (so that any .cpp program can #include <glm/glm.hpp>). If you are using Arch Linux, you can install it like so (for other linux distributives it should be similar):

sudo pacman -S glm

And you should have texlive installed (including pdflatex and ams packages). You could go for a smaller install or install just install whole tex (which is not small, I gotta say), but that’s what I did, so it is likely to work:

sudo pacman -S texlive-full

And then you just place the header in your project (for now it’s a header only library), or you can install it system-wide by copying it to /usr/local/include/ like so:

git clone https://github.com/alexpaniman/cppgfplots.git

cd cppgfplots
sudo cp cppgfplots/cppgfplots.h /usr/local/include/

Note you have to compile it with C++20 or later enabled as it uses some new features.