Make a hex grid.

This uses a grid factory method to build an infinite 2-D grid of hexagons with pitch equal to 1.0 cm.

Learn more about grids.

import math

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from matplotlib.collections import PatchCollection

from armi.reactor import grids
from armi import configure

configure(permissive=True)

hexes = grids.HexGrid.fromPitch(1.0)

polys = []
fig, ax = plt.subplots()
ax.set_aspect("equal")
ax.set_axis_off()

for hex_i in hexes.generateSortedHexLocationList(127):
    x, y, z = hex_i.getGlobalCoordinates()
    ax.text(x, y, f"{hex_i.i},{hex_i.j}", ha="center", va="center", fontsize=8)
    polys.append(
        mpatches.RegularPolygon(
            (x, y), numVertices=6, radius=1 / math.sqrt(3), orientation=math.pi / 2
        )
    )
patches = PatchCollection(polys, fc="white", ec="k")
ax.add_collection(patches)

# create a bounding box around patches with a small margin (2%)
bbox = patches.get_datalim(ax.transData)
bbox = bbox.expanded(1.02, 1.02)
ax.set_xlim(bbox.xmin, bbox.xmax)
ax.set_ylim(bbox.ymin, bbox.ymax)
ax.set_title("(i, j) indices for a hex grid")
plt.show()