def __init__(self, ex: Union[str, Number, sympy.Expr]) -> None:
"""Create an Expression object.
Receives the mathematical expression which shall be represented by the object as a string
which will be parsed using py_expression_eval. For available operators, functions and
constants see SymPy documentation
Args:
ex (string): The mathematical expression represented as a string
"""
super().__init__()
if isinstance(ex, sympy.Expr):
self._original_expression = None
self._sympified_expression = ex
self._variables = get_variables(self._sympified_expression)
elif isinstance(ex, ExpressionScalar):
self._original_expression = ex._original_expression
self._sympified_expression = ex._sympified_expression
self._variables = ex._variables
elif isinstance(ex, (int, float)):
self._original_expression = ex
self._sympified_expression = sympify(ex)
self._variables = ()
else:
self._original_expression = ex
self._sympified_expression = sympify(ex)
self._variables = get_variables(self._sympified_expression)
self._exact_rational_lambdified = None
def evaluate(self, expression: Union[sympy.Expr, np.ndarray], parameters):
if isinstance(expression, np.ndarray):
variables = set.union(
*map(set, map(get_variables, expression.flat)))
else:
variables = get_variables(expression)
return evaluate_lamdified_exact_rational(expression,
variables=list(variables),
parameters=parameters,
lambdified=None)[0]
def test_get_variables_indexed(self):
expr = a_[i] * IndexedBase(a * b)[j]
self.assertEqual({'a', 'b', 'i', 'j'}, set(get_variables(expr)))
def test_get_variables(self):
expr = a * b / 5
self.assertEqual({'a', 'b'}, set(get_variables(expr)))
