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geomotif.demo

Demo entry point: generate a few spirals and plot them with matplotlib.

Installed as the geomotif-demo console command; also runnable as python -m geomotif. Requires the plotting extra (pip install 'geomotif[plot]').

Usage::

geomotif-demo             # open an interactive plot window
geomotif-demo out.png     # save the figure to a file instead

Functions:

Name Description
main

Plot the showcase grid, or save it to the file named on the command line.

main 

main(argv: list[str] | None = None) -> None

Plot the showcase grid, or save it to the file named on the command line.

Source code in src/geomotif/demo.py 
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def main(argv: list[str] | None = None) -> None:
    """Plot the showcase grid, or save it to the file named on the command line."""
    try:
        from .plotting import Panel, plot_grid
    except ImportError:
        raise SystemExit("The demo needs matplotlib: pip install 'geomotif[plot]'") from None

    args = sys.argv[1:] if argv is None else argv

    panels: list[Panel] = []
    for title, motif, spacing in EXAMPLES:
        # A dense equal-spaced copy of the same geometry is drawn as the
        # smooth guide line under the sample points.
        extra = {"center": motif.center, "guide": motif.generate(800)}
        panels.append((title, motif.generate(120, spacing=spacing), extra))

    fig = plot_grid(
        panels,
        ncols=2,
        suptitle="geomotif demo",
        show_points=True,
        label_endpoints=True,
    )

    if args:
        out = args[0]
        fig.savefig(out, dpi=150, facecolor=fig.get_facecolor())
        print(f"saved {out}")
        return

    import matplotlib
    import matplotlib.pyplot as plt

    # File-only backends can't open a window; fall back to saving a PNG
    # instead of show()ing into the void.
    if matplotlib.get_backend().lower() in {
        "agg",
        "pdf",
        "ps",
        "svg",
        "pgf",
        "template",
        "cairo",
    }:
        out = "spiral-demo.png"
        fig.savefig(out, dpi=150, facecolor=fig.get_facecolor())
        print(
            f"No GUI backend available for matplotlib — saved {out} instead.\n"
            "To get an interactive window, install one of:\n"
            "  pip install PyQt6        (inside this venv)\n"
            "  your OS's Tk package     (e.g. 'sudo pacman -S tk', "
            "'sudo apt install python3-tk')"
        )
    else:
        plt.show()