oliverlee · December 17, 2020 17:27
diff --git a/woodblock.py b/woodblock.py
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 """Determine rough estimates for material requirements."""
 from dataclasses import dataclass
 from sympy import Symbol


 @dataclass
 class Body:
    width: Symbol
    length: Symbol
    height: Symbol
    density: Symbol

    @property
    def mass(self):
        return self.width * self.length * self.height * self.density


 usage = f"""usage: {__file__} <width> <height> <mass> <wood_density> <weight_density>

 Args:
    width: Width of the block's square base [cm]
    height: Height of the block [cm]
    mass: Mass of the block [g]
    wood_density: Density of the exterior wood material [g/cm3]
    weight_density: Density of the interior weight material [g/cm3]

 Calculate rough estimates for material requirements of a wood-block pattern
 weight.
 see: https://www.metermeter.dk/wood-block-pattern-weight.html

 where:
    s: Width of the cubic weight [cm]
    t_x: Wall thickness of the wood exterior along its width [cm]
    t_z: Wall thickness of the wood exterior along its height [cm]
 """

 if __name__ == "__main__":
    import sys

    if len(sys.argv) < 6:
        print(usage)
        sys.exit(1)

    width, height, mass, wood_density, weight_density = sys.argv[1:6]

    from sympy import solve, symbols

    w, h, m, rho1, rho2 = symbols("w h m ρ_1 ρ_2", real=True, positive=True)
    s, tx, tz = deps = symbols("s t_x t_z", real=True, positive=True)

    wood_exterior = Body(w, w, h, rho1)
    wood_interior = Body(s, s, s, rho1)
    weight = Body(s, s, s, rho2)

    mass_constraint = wood_exterior.mass - wood_interior.mass + weight.mass - m
    position_constraint_xy = 2 * tx + s - w
    position_constraint_z = 2 * tz + s - h

    equations = [
        eqn.subs(
            {w: width, h: height, m: mass, rho1: wood_density, rho2: weight_density}
        )
        for eqn in (mass_constraint, position_constraint_xy, position_constraint_z)
    ]

    soln = solve(equations, deps, dict=True,)

    if not soln:
        print("Unable to solve.")
        sys.exit(1)

    print(f"s: {soln[0][s]:.2f} cm")
    print(f"t_x: {soln[0][tx]:.2f} cm")
    print(f"t_z: {soln[0][tz]:.2f} cm")
    sys.exit()
	#!/usr/bin/env python3
	# -- coding: utf-8 --
	"""Determine rough estimates for material requirements."""
	from dataclasses import dataclass
	from sympy import Symbol


	@dataclass
	class Body:
	width: Symbol
	length: Symbol
	height: Symbol
	density: Symbol

	@property
	def mass(self):
	return self.width * self.length * self.height * self.density


	usage = f"""usage: {__file__} <width> <height> <mass> <wood_density> <weight_density>

	Args:
	width: Width of the block's square base [cm]
	height: Height of the block [cm]
	mass: Mass of the block [g]
	wood_density: Density of the exterior wood material [g/cm3]
	weight_density: Density of the interior weight material [g/cm3]

	Calculate rough estimates for material requirements of a wood-block pattern
	weight.
	see: https://www.metermeter.dk/wood-block-pattern-weight.html

	where:
	s: Width of the cubic weight [cm]
	t_x: Wall thickness of the wood exterior along its width [cm]
	t_z: Wall thickness of the wood exterior along its height [cm]
	"""

	if __name__ == "__main__":
	import sys

	if len(sys.argv) < 6:
	print(usage)
	sys.exit(1)

	width, height, mass, wood_density, weight_density = sys.argv[1:6]

	from sympy import solve, symbols

	w, h, m, rho1, rho2 = symbols("w h m ρ_1 ρ_2", real=True, positive=True)
	s, tx, tz = deps = symbols("s t_x t_z", real=True, positive=True)

	wood_exterior = Body(w, w, h, rho1)
	wood_interior = Body(s, s, s, rho1)
	weight = Body(s, s, s, rho2)

	mass_constraint = wood_exterior.mass - wood_interior.mass + weight.mass - m
	position_constraint_xy = 2 * tx + s - w
	position_constraint_z = 2 * tz + s - h

	equations = [
	eqn.subs(
	{w: width, h: height, m: mass, rho1: wood_density, rho2: weight_density}
	)
	for eqn in (mass_constraint, position_constraint_xy, position_constraint_z)
	]

	soln = solve(equations, deps, dict=True,)

	if not soln:
	print("Unable to solve.")
	sys.exit(1)

	print(f"s: {soln[0][s]:.2f} cm")
	print(f"t_x: {soln[0][tx]:.2f} cm")
	print(f"t_z: {soln[0][tz]:.2f} cm")
	sys.exit()