# Add implicit multiplication operators, e.g. '5x' -> '5*x'.
string = LinExpr._RE_NUM_VAR.sub(r'\1*\2', string)
tree = ast.parse(string, 'eval')
- expr = cls._fromast(tree)
- if not isinstance(expr, cls):
+ expression = cls._fromast(tree)
+ if not isinstance(expression, cls):
raise SyntaxError('invalid syntax')
- return expr
+ return expression
def __repr__(self):
string = ''
string += ' - {}'.format(-constant)
return string
- def _repr_latex_(self):
- string = ''
- for i, (symbol, coefficient) in enumerate(self.coefficients()):
- if coefficient == 1:
- if i != 0:
- string += ' + '
- elif coefficient == -1:
- string += '-' if i == 0 else ' - '
- elif i == 0:
- string += '{}'.format(coefficient._repr_latex_().strip('$'))
- elif coefficient > 0:
- string += ' + {}'.format(coefficient._repr_latex_().strip('$'))
- elif coefficient < 0:
- string += ' - {}'.format((-coefficient)._repr_latex_().strip('$'))
- string += '{}'.format(symbol._repr_latex_().strip('$'))
- constant = self.constant
- if len(string) == 0:
- string += '{}'.format(constant._repr_latex_().strip('$'))
- elif constant > 0:
- string += ' + {}'.format(constant._repr_latex_().strip('$'))
- elif constant < 0:
- string += ' - {}'.format((-constant)._repr_latex_().strip('$'))
- return '$${}$$'.format(string)
-
def _parenstr(self, always=False):
string = str(self)
if not always and (self.isconstant() or self.issymbol()):
return '({})'.format(string)
@classmethod
- def fromsympy(cls, expr):
+ def fromsympy(cls, expression):
"""
Create a linear expression from a SymPy expression. Raise TypeError is
the sympy expression is not linear.
import sympy
coefficients = []
constant = 0
- for symbol, coefficient in expr.as_coefficients_dict().items():
+ for symbol, coefficient in expression.as_coefficients_dict().items():
coefficient = Fraction(coefficient.p, coefficient.q)
if symbol == sympy.S.One:
constant = coefficient
symbol = Symbol(symbol.name)
coefficients.append((symbol, coefficient))
else:
- raise TypeError('non-linear expression: {!r}'.format(expr))
- expr = LinExpr(coefficients, constant)
- if not isinstance(expr, cls):
+ raise TypeError('non-linear expression: {!r}'.format(expression))
+ expression = LinExpr(coefficients, constant)
+ if not isinstance(expression, cls):
raise TypeError('cannot convert to a {} instance'.format(cls.__name__))
- return expr
+ return expression
def tosympy(self):
"""
Convert the linear expression to a SymPy expression.
"""
import sympy
- expr = 0
+ expression = 0
for symbol, coefficient in self.coefficients():
term = coefficient * sympy.Symbol(symbol.name)
- expr += term
- expr += self.constant
- return expr
+ expression += term
+ expression += self.constant
+ return expression
class Symbol(LinExpr):
def __repr__(self):
return self.name
- def _repr_latex_(self):
- return '$${}$$'.format(self.name)
-
def symbols(names):
"""
def __repr__(self):
return '_{}'.format(self.name)
- def _repr_latex_(self):
- return '$${}_{{{}}}$$'.format(self.name, self._index)
-
class Rational(LinExpr, Fraction):
"""
return '{!r}'.format(self.numerator)
else:
return '{!r}/{!r}'.format(self.numerator, self.denominator)
-
- def _repr_latex_(self):
- if self.denominator == 1:
- return '$${}$$'.format(self.numerator)
- elif self.numerator < 0:
- return '$$-\\frac{{{}}}{{{}}}$$'.format(-self.numerator,
- self.denominator)
- else:
- return '$$\\frac{{{}}}{{{}}}$$'.format(self.numerator,
- self.denominator)