graphlib

A modern C++20 plotting library that mimics matplotlib — same names, same defaults, same look.

If you know import matplotlib.pyplot as plt, you already know graphlib:

#include <graphlib/pyplot.hpp>
#include <graphlib/util.hpp>
namespace plt = graphlib::pyplot;

int main() {
    const auto x = graphlib::linspace(0.0, 2.0 * std::numbers::pi, 200);
    std::vector<double> y(x.size());
    for (size_t i = 0; i < x.size(); ++i) y[i] = std::sin(x[i]);

    plt::plot(x, y, {.linewidth = 2.0, .label = "sin(x)"});
    plt::title("Hello graphlib");
    plt::xlabel("x [rad]");
    plt::grid(true);
    plt::savefig("hello.svg");
}

Same tab10 colors, same tick algorithm (a faithful port of MaxNLocator), same 5% margins, same dash patterns, same label formatting — pinned by oracle fixtures generated from matplotlib itself.

Status: v0.7 "Fast Path"

Fast: matplotlib's path simplification and marker stamping ported — a 10M-point line saves to PNG in ~270 ms, a 1M-point scatter draws in ~190 ms, with a benchmark regression gate in CI. SVG, PNG and PDF output — the PDF is vector, byte-deterministic, with selectable text (embedded DejaVu, CID-keyed) — plus mathtext ($\frac{a}{b}$, scripts, greek, \sum limits, \sqrt) in every text element, date axes (AutoDateLocator + ConciseDateFormatter on std::chrono), and annotate with matplotlib's arrow styles. Underneath: the everyday workhorses (plot/scatter/bar/hist/ fill_between/errorbar/step/pie, spans), subplots + GridSpec with sharing and twins, tight_layout, log scales with minor ticks, legend(loc="best"), rcParams + style sheets, and the 2D field tools (imshow, pcolormesh, contour/contourf, colorbar) with oracle-exact colormaps. Interactive GLFW windows with pan/zoom and FuncAnimation behind -DGRAPHLIB_INTERACTIVE=ON. Tick, autoscale, date and colormap algorithms are faithful ports pinned by fixtures generated from matplotlib itself. See ROADMAP.md for the ladder to 1.0 and docs/PARITY.md for coverage.

Zero mandatory dependencies. Platforms: macOS (arm64), Linux (x86_64, arm64), Windows (x86_64, arm64).

Build & play

git clone <this repo> && cd graphlib
cmake --preset release && cmake --build --preset release
./build/release/examples/01_hello_lines   # -> hello.svg, open in any browser

Or consume from your own CMake project — three ways, all ending in target_link_libraries(your_app PRIVATE graphlib::graphlib):

# 1. FetchContent
include(FetchContent)
FetchContent_Declare(graphlib
    GIT_REPOSITORY https://github.com/Nosenzor/graphlib.git GIT_TAG v1.0.1)
FetchContent_MakeAvailable(graphlib)

# 2. Install + find_package
cmake --preset release && cmake --build --preset release
cmake --install build/release --prefix /your/prefix
# then in your project: find_package(graphlib 1.0 REQUIRED) with CMAKE_PREFIX_PATH=/your/prefix

// 3. vcpkg — this repository is itself a vcpkg git registry. Add to
//    vcpkg-configuration.json next to your vcpkg.json, then list "graphlib"
//    in the manifest's "dependencies" and build with the vcpkg toolchain.
{
  "registries": [
    {
      "kind": "git",
      "repository": "https://github.com/Nosenzor/graphlib",
      "baseline": "",
      "packages": ["graphlib"]
    }
  ]
}

The port is static-only, builds with an external stb, and installs graphlib::graphlib — the same target as the other two paths. (For a quick local try without a manifest: vcpkg install graphlib --overlay-ports=path/to/graphlib/ports.) Submission to the central vcpkg registry is gated on project maturity and AGG devendoring — see docs/decisions/VCPKG-SUBMISSION-PLAN.md.

Tests (ctest --preset dev) compare against committed matplotlib-oracle fixtures and golden SVG baselines. Contributor guide: AGENTS.md. Architecture: docs/DESIGN.md.

License

MIT