def test_add_variable(self):
o = Variable('o', 10)
a = Expression(o, 20, 2)
v = Variable('v', 20)
self.assertEqual(len(a.terms), 1)
self.assertAlmostEqual(a.terms.get(o), 20.0)
# implicit coefficient of 1
a.add_variable(v)
self.assertEqual(len(a.terms), 2)
self.assertAlmostEqual(a.terms.get(v), 1.0)
# add again, with different coefficient
a.add_variable(v, 2.0)
self.assertEqual(len(a.terms), 2)
self.assertAlmostEqual(a.terms.get(v), 3.0)
# add again, with resulting 0 coefficient. should remove the term.
a.add_variable(v, -3)
self.assertEqual(len(a.terms), 1)
self.assertIsNone(a.terms.get(v))
# try adding the removed term back, with 0 coefficient
a.add_variable(v, 0)
self.assertEqual(len(a.terms), 1)
self.assertIsNone(a.terms.get(v))
def test_coefficient_for(self):
va = Variable('a', 10)
vb = Variable('b', 20)
a = Expression(va, 20, 2)
self.assertEqual(a.coefficient_for(va), 20)
self.assertEqual(a.coefficient_for(vb), 0)
def test_coefficient_for(self):
va = Variable('a', 10)
vb = Variable('b', 20)
a = Expression(va, 20, 2)
self.assertEqual(a.coefficient_for(va), 20)
self.assertEqual(a.coefficient_for(vb), 0)
def test_add_expression_variable(self):
a = Expression(Variable('o', 10), 20, 2)
v = Variable('v', 20)
# should work just like add_variable
a.add_expression(v, 2)
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.terms.get(v), 2)
def test_clone(self):
v = Variable('v', 10)
expr = Expression(v, 20, 2)
clone = expr.clone()
self.assertEqual(clone.constant, expr.constant)
self.assertEqual(len(clone.terms), len(expr.terms))
self.assertEqual(clone.terms.get(v), 20)
def test_clone(self):
v = Variable('v', 10)
expr = Expression(v, 20, 2)
clone = expr.clone()
self.assertEqual(clone.constant, expr.constant)
self.assertEqual(len(clone.terms), len(expr.terms))
self.assertEqual(clone.terms.get(v), 20)
def test_new_subject(self):
v = Variable('v', 10)
e = Expression(v, 2, 5)
self.assertEqual(e.new_subject(v), 0.5)
self.assertEqual(e.constant, -2.5)
self.assertIsNone(e.terms.get(v))
self.assertTrue(e.is_constant)
def test_add_expression_variable(self):
a = Expression(Variable('o', 10), 20, 2)
v = Variable('v', 20)
# should work just like add_variable
a.add_expression(v, 2)
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.terms.get(v), 2)
def test_new_subject(self):
v = Variable('v', 10)
e = Expression(v, 2, 5)
self.assertEqual(e.new_subject(v), 0.5)
self.assertEqual(e.constant, -2.5)
self.assertIsNone(e.terms.get(v))
self.assertTrue(e.is_constant)
def test_change_subject(self):
va = Variable('a', 10)
vb = Variable('b', 5)
e = Expression(va, 2, 5)
e.change_subject(vb, va)
self.assertEqual(e.constant, -2.5)
self.assertIsNone(e.terms.get(va))
self.assertEqual(e.terms.get(vb), 0.5)
def test_expression_with_reused_variables(self):
e1 = Expression(constant=10)
e2 = Expression(Variable(name='c', value=10), 2, 4)
ieq = Constraint(e1, Constraint.GEQ, e2)
self.assertExpressionEqual(ieq.expression, e1 - e2)
ieq = Constraint(e1, Constraint.LEQ, e2)
self.assertExpressionEqual(ieq.expression, e2 - e1)
def test_change_subject(self):
va = Variable('a', 10)
vb = Variable('b', 5)
e = Expression(va, 2, 5)
e.change_subject(vb, va)
self.assertEqual(e.constant, -2.5)
self.assertIsNone(e.terms.get(va))
self.assertEqual(e.terms.get(vb), 0.5)
def test_is_constant(self):
e1 = Expression()
e2 = Expression(constant=10)
e3 = Expression(Variable('o', 10), 20)
e4 = Expression(Variable('o', 10), 20, 2)
self.assertTrue(e1.is_constant)
self.assertTrue(e2.is_constant)
self.assertFalse(e3.is_constant)
self.assertFalse(e4.is_constant)
def test_add_variable(self):
o = Variable('o', 10)
a = Expression(o, 20, 2)
v = Variable('v', 20)
self.assertEqual(len(a.terms), 1)
self.assertAlmostEqual(a.terms.get(o), 20.0)
# implicit coefficient of 1
a.add_variable(v)
self.assertEqual(len(a.terms), 2)
self.assertAlmostEqual(a.terms.get(v), 1.0)
# add again, with different coefficient
a.add_variable(v, 2.0)
self.assertEqual(len(a.terms), 2)
self.assertAlmostEqual(a.terms.get(v), 3.0)
# add again, with resulting 0 coefficient. should remove the term.
a.add_variable(v, -3)
self.assertEqual(len(a.terms), 1)
self.assertIsNone(a.terms.get(v))
# try adding the removed term back, with 0 coefficient
a.add_variable(v, 0)
self.assertEqual(len(a.terms), 1)
self.assertIsNone(a.terms.get(v))
def test_variable_expression(self):
x = Variable('x', 167)
expr = Expression(x)
self.assertExpressionEqual(expr, 'x[167.0]')
self.assertAlmostEqual(expr.constant, 0.0)
self.assertEqual(len(expr.terms), 1)
self.assertAlmostEqual(expr.terms.get(x), 1.0)
expr = Expression(x, 3)
self.assertExpressionEqual(expr, '3.0*x[167.0]')
self.assertAlmostEqual(expr.constant, 0.0)
self.assertEqual(len(expr.terms), 1)
self.assertAlmostEqual(expr.terms.get(x), 3.0)
def test_any_pivotable_variable(self):
# t.e(c.InternalError, Expression(10), 'any_pivotable_variable')
e = Expression(constant=10)
with self.assertRaises(InternalError):
e.any_pivotable_variable()
# t.e(c.InternalError, Expression(10), 'any_pivotable_variable')
va = Variable('a', 10)
vb = SlackVariable('slack', 1)
a = Expression(va, 20, 2)
self.assertIsNone(a.any_pivotable_variable())
a.set_variable(vb, 2)
self.assertEqual(vb, a.any_pivotable_variable())
def test_constructor_with_variable_operator_expression_args2(self):
v = Variable(name='v', value=10)
e = Expression(Variable(name='x', value=5), 2, 4)
ieq = Constraint(e, Constraint.GEQ, v)
self.assertExpressionEqual(ieq.expression, e - v)
ieq = Constraint(e, Constraint.LEQ, v)
self.assertExpressionEqual(ieq.expression, v - e)
def test_substitute_out(self):
v1 = Variable('1', 20)
v2 = Variable('2', 2)
a = Expression(v1, 2, 2) # 2*v1 + 2
# new variable
a.substitute_out(v1, Expression(v2, 4, 4))
self.assertEqual(a.constant, 10)
self.assertIsNone(a.terms.get(v1))
self.assertEqual(a.terms.get(v2), 8)
# existing variable
a.set_variable(v1, 1)
a.substitute_out(v2, Expression(v1, 2, 2))
self.assertEqual(a.constant, 26)
self.assertIsNone(a.terms.get(v2))
self.assertEqual(a.terms.get(v1), 17)
def test_set_variable(self):
va = Variable('a', 10)
vb = Variable('b', 20)
a = Expression(va, 20, 2)
# set existing variable
a.set_variable(va, 2)
self.assertEqual(len(a.terms), 1)
self.assertEqual(a.coefficient_for(va), 2)
# set new variable
a.set_variable(vb, 2)
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.coefficient_for(vb), 2)
def test_any_pivotable_variable(self):
# t.e(c.InternalError, Expression(10), 'any_pivotable_variable')
e = Expression(constant=10)
with self.assertRaises(InternalError):
e.any_pivotable_variable()
# t.e(c.InternalError, Expression(10), 'any_pivotable_variable')
va = Variable('a', 10)
vb = SlackVariable('slack', 1)
a = Expression(va, 20, 2)
self.assertIsNone(a.any_pivotable_variable())
a.set_variable(vb, 2)
self.assertEqual(vb, a.any_pivotable_variable())
def test_set_variable(self):
va = Variable('a', 10)
vb = Variable('b', 20)
a = Expression(va, 20, 2)
# set existing variable
a.set_variable(va, 2)
self.assertEqual(len(a.terms), 1)
self.assertEqual(a.coefficient_for(va), 2)
# set new variable
a.set_variable(vb, 2)
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.coefficient_for(vb), 2)
def test_add(self):
x = Variable('x', 167)
y = Variable('y', 42)
# Add a constant to an expression
self.assertExpressionEqual(Expression(x) + 2, '2.0 + x[167.0]')
self.assertExpressionEqual(3 + Expression(x), '3.0 + x[167.0]')
# Add a variable to an expression
self.assertExpressionEqual(y + Expression(x), 'x[167.0] + y[42.0]')
self.assertExpressionEqual(Expression(x) + y, 'x[167.0] + y[42.0]')
# Add an expression to an expression
self.assertExpressionEqual(
Expression(x) + Expression(y), 'x[167.0] + y[42.0]')
self.assertExpressionEqual(
Expression(x, 20, 2) + Expression(y, 10, 5),
'7.0 + 20.0*x[167.0] + 10.0*y[42.0]')
def test_from_constant(self):
"Constraint can be constructed from a constant expression"
ex = Expression(constant=10)
# Constant value is ported to a float.
self.assertIsInstance(ex.constant, float)
self.assertAlmostEqual(ex.constant, 10.0)
c1 = Constraint(ex)
self.assertExpressionEqual(c1.expression, ex)
self.assertFalse(c1.is_inequality)
c2 = Constraint(10)
self.assertAlmostEqual(c2.expression.constant, 10)
self.assertTrue(c2.expression.is_constant)
self.assertFalse(c2.is_inequality)
def test_sub(self):
x = Variable('x', 167)
y = Variable('y', 42)
# Subtract a constant from an expression
self.assertExpressionEqual(Expression(x) - 2, '-2.0 + x[167.0]')
self.assertExpressionEqual(3 - Expression(x), '3.0 + -1.0*x[167.0]')
# Subtract a variable from an expression
self.assertExpressionEqual(y - Expression(x),
'-1.0*x[167.0] + y[42.0]')
self.assertExpressionEqual(
Expression(x) - y, 'x[167.0] + -1.0*y[42.0]')
# Subtract an expression from an expression
self.assertExpressionEqual(
Expression(x) - Expression(y), 'x[167.0] + -1.0*y[42.0]')
self.assertExpressionEqual(
Expression(x, 20, 2) - Expression(y, 10, 5),
'-3.0 + 20.0*x[167.0] + -10.0*y[42.0]')
def test_substitute_out(self):
v1 = Variable('1', 20)
v2 = Variable('2', 2)
a = Expression(v1, 2, 2) # 2*v1 + 2
# new variable
a.substitute_out(v1, Expression(v2, 4, 4))
self.assertEqual(a.constant, 10)
self.assertIsNone(a.terms.get(v1))
self.assertEqual(a.terms.get(v2), 8)
# existing variable
a.set_variable(v1, 1)
a.substitute_out(v2, Expression(v1, 2, 2))
self.assertEqual(a.constant, 26)
self.assertIsNone(a.terms.get(v2))
self.assertEqual(a.terms.get(v1), 17)
def test_add_expression(self):
va = Variable('a', 10)
vb = Variable('b', 20)
vc = Variable('c', 5)
a = Expression(va, 20, 2)
# different variable and implicit coefficient of 1, should make new term
a.add_expression(Expression(vb, 10, 5))
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.constant, 7)
self.assertEqual(a.terms.get(vb), 10)
# same variable, should reuse existing term
a.add_expression(Expression(vb, 2, 5))
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.constant, 12)
self.assertEqual(a.terms.get(vb), 12)
# another variable and a coefficient,
# should multiply the constant and all terms in the new expression
a.add_expression(Expression(vc, 1, 2), 2)
self.assertEqual(len(a.terms), 3)
self.assertEqual(a.constant, 16)
self.assertEqual(a.terms.get(vc), 2)
def test_mul(self):
x = Variable('x', 167)
y = Variable('y', 42)
# Multiply an expression by a constant
self.assertExpressionEqual(Expression(x) * 2, '2.0*x[167.0]')
self.assertExpressionEqual(3 * Expression(x), '3.0*x[167.0]')
# Can't multiply an expression by a variable unless the expression is a constant
with self.assertRaises(TypeError):
y * Expression(x)
with self.assertRaises(TypeError):
Expression(x) * y
self.assertExpressionEqual(x * Expression(constant=2), '2.0*x[167.0]')
self.assertExpressionEqual(Expression(constant=3) * x, '3.0*x[167.0]')
# Can't multiply an expression by an expression unless
# one of the expressions is a constant.
with self.assertRaises(TypeError):
Expression(x) * Expression(y)
with self.assertRaises(TypeError):
Expression(x, 20, 2) * Expression(y, 10, 5)
self.assertExpressionEqual(
Expression(x, 20, 2) * Expression(constant=5),
'10.0 + 100.0*x[167.0]')
self.assertExpressionEqual(
Expression(x, 20) * Expression(constant=5), '100.0*x[167.0]')
self.assertExpressionEqual(
Expression(constant=2) * Expression(y, 10, 5),
'10.0 + 20.0*y[42.0]')
self.assertExpressionEqual(
Expression(constant=2) * Expression(y, 10), '20.0*y[42.0]')
def test_variable_expression(self):
"Variable expressions can be constructed"
x = Variable('x', 167)
y = Variable('y', 2)
cly = Expression(y)
cly.add_expression(x)
def test_works_with_nested_expressions(self):
e1 = Expression(constant=10)
e2 = Expression(Variable(name='z', value=10), 2, 4)
eq = Constraint(e1, Constraint.EQ, e2)
self.assertExpressionEqual(eq.expression, e1 - e2)
def test_equations_in_place_of_variables(self):
e = Expression(constant=10)
v = Variable(name='v', value=22)
eq = Constraint(e, Constraint.EQ, v)
self.assertExpressionEqual(eq.expression, 10 - v)
def test_inequality_expression_instantiation(self):
e = Expression(constant=10)
ieq = Constraint(e)
self.assertExpressionEqual(ieq.expression, e)
def test_constant_expression(self):
expr = Expression(constant=4)
self.assertExpressionEqual(expr, '4.0')
self.assertAlmostEqual(expr.constant, 4.0)
self.assertEqual(len(expr.terms), 0)
def test_variable_expression(self):
"Variable expressions can be constructed"
x = Variable('x', 167)
y = Variable('y', 2)
cly = Expression(y)
cly.add_expression(x)
def test_multiply(self):
v = Variable('v', 10)
expr = Expression(v, 20, 2)
expr.multiply(-1)
self.assertExpressionEqual(expr, '-2.0 + -20.0*v[10.0]')
def test_multiply(self):
v = Variable('v', 10)
expr = Expression(v, 20, 2)
expr.multiply(-1)
self.assertExpressionEqual(expr, '-2.0 + -20.0*v[10.0]')
def test_empty_expression(self):
expr = Expression()
self.assertExpressionEqual(expr, '0.0')
self.assertAlmostEqual(expr.constant, 0.0)
self.assertEqual(len(expr.terms), 0)
def test_add_expression(self):
va = Variable('a', 10)
vb = Variable('b', 20)
vc = Variable('c', 5)
a = Expression(va, 20, 2)
# different variable and implicit coefficient of 1, should make new term
a.add_expression(Expression(vb, 10, 5))
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.constant, 7)
self.assertEqual(a.terms.get(vb), 10)
# same variable, should reuse existing term
a.add_expression(Expression(vb, 2, 5))
self.assertEqual(len(a.terms), 2)
self.assertEqual(a.constant, 12)
self.assertEqual(a.terms.get(vb), 12)
# another variable and a coefficient,
# should multiply the constant and all terms in the new expression
a.add_expression(Expression(vc, 1, 2), 2)
self.assertEqual(len(a.terms), 3)
self.assertEqual(a.constant, 16)
self.assertEqual(a.terms.get(vc), 2)
