"""
from topy.optimizer import Optimizer
import numpy as np
# Initialize problem
opt = Optimizer('cylinder', 0.1, void_density = 0.001, max_iterations=50)
ex, ey, ez = 20, 20, 10
opt.set_problem_dimensions(ex, ey, ez)
# Create cylinder by removing material around
z0 = ez/2
x0, y0, r0 = ex/2+0.5,ey/2+.5,ex/2-1
x, y, z = opt.element_indices
mask = opt.elements[(x-x0)**2+(y-y0)**2>=r0**2]
opt.add_passive_elements(mask)
# Create hole in the middle:
r1 = r0/3
mask = opt.elements[(x-x0)**2+(y-y0)**2<=r1**2]
opt.add_passive_elements(mask)
# Fix points in center
bearing1 = opt.nodes[x0+r1+1,y0+1-1:y0+1+2,z0+1-1:z0+1+2]
bearing2 = opt.nodes[x0-r1+1,y0+1-1:y0+1+2,z0+1-1:z0+1+2]
opt.fix_nodes(bearing1, directions = ['x', 'y', 'z'])
opt.fix_nodes(bearing2, directions = ['x', 'y', 'z'])
