Rectangle Packaging Problem / Efficient 2D Packing

from rectpack import newPacker
import pandas
import jinja2
import numpy as np
import pprint
import click


def main(rects, width, length, bins=1):
    packer = newPacker()

    for rect in rects:
        packer.add_rect(*rect)

    for i in range(bins):
        packer.add_bin(width, length)
    packer.pack()

    all_rects = packer.rect_list()
    if len(all_rects) != len(rects):
        raise UserWarning("Cant fit rectangles %d/%d", len(all_rects), len(rects))

    dfout = {"bin": [], "x": [], "y":[], "w":[], "h":[], "area":[], "rotation":[]}
    for rect, transform in zip(rects, all_rects):
        b, x, y, w, h, rid = transform
        dfout["bin"].append(b)
        dfout["x"].append(x)
        dfout["y"].append(y)
        dfout["w"].append(w)
        dfout["h"].append(h)
        dfout["area"].append(h*w)

        for rect in rects:
            if (rect[0] == w and rect[1] == h):
                dfout["rotation"].append(0)
                break
            elif (rect[0] == h and rect[1] == w):
                dfout["rotation"].append(90)
                break
            else:
                print("error ", rect, transform)
                assert(0, "part not in expected order")

    return dfout


def to_scad(df):
    '''
    Return scad as a string
    '''
    template = '''function get_shapes() = [
        {% for _, l in df.iterrows() -%}
        [{{l['bin']}}, {{l['x']}}, {{l['y']}}, {{l['w']}}, {{l['h']}}],
        {% endfor %}
    ];
    '''
    return jinja2.Template(template).render(df=df)



def optimize(panels, max_bins):
    config = {"nbins": [], "panel width": [], "panel length": [], "packing": [], "% used": []}
    dfset = pandas.read_csv(f"rectangles.csv")
    rect_set = [[line["width"], line["length"], line["name"]] for _, line in dfset.iterrows()]

    for panel in panels:
        for nbin in range(1, max_bins+1):
            nsets = 1
            while True:
                try:
                    d = main(list(rect_set)*nsets, width=panel[0], length=panel[1], bins=nbin)
                    df = pandas.DataFrame(d)
                    config["packing"].append(df)
                    config["nbins"].append(nbin)
                    config["panel width"].append(panel[0])
                    config["panel length"].append(panel[1])
                    config["% used"].append(sum(df["w"]*df["h"])/(nbin*panel[0]*panel[1]))
                    nsets+=1
                except UserWarning:
                    break

    return pandas.DataFrame(config)


@click.command()
@click.option("--bins", "-n", type=int, default=1)
@click.option("--design", required=True)
@click.option("--output-scad", default="shapes.scad")
@click.option("--output-xlsx", default="shapes.xlsx")
def click_main(bins, design, output_scad, output_xlsx):
    panels = [
        [11.5, 35.5],
        [23.5, 35.5],
    ]

    config_df = optimize(panels=panels, max_bins=bins)
    max_percent = np.max(config_df["% used"])
    i = list(config_df["% used"]).index(max_percent)
    df = config_df.iloc[i]
    df_shapes = df["packing"]
    df_shapes.to_excel(output_xlsx)
    with open(output_scad, "w") as f:
        f.write(to_scad(df_shapes))

    pprint.pprint(list(config_df["% used"]))
    pprint.pprint(config_df)
    print(f"Min Error: {max_percent}\n Panel Size: {df['panel width']}x{df['panel length']}. nbins: {df['nbins']}")


click_main()

use <./shapes.scad>;

/*
# b - Bin index
# x - Rectangle bottom-left corner x coordinate
# y - Rectangle bottom-left corner y coordinate
# w - Rectangle width
# h - Rectangle height
# rid - User asigned rectangle id or None
*/

bins = 8;
width = 24;
gap=0.5;
length=36;
space = 25;
difference() {
    for (i=[0:bins-1]) {
        translate([(width+space)*i, 0])square([width,length]);
    };
    union() {
        for (shape=get_shapes()) {
            translate([shape[1]+(width+space)*shape[0]+gap/2, shape[2]+gap/2])square([shape[3], shape[4]], center=false);
        };
    };
};
echo(len(get_shapes()));

python3 pack.py --design rectangles.csv --bins 8

Min Error: 0.9099990010987913
Panel Size: 23.5x35.5. nbins: 3