X-Git-Url: https://scm.cri.ensmp.fr/git/linpy.git/blobdiff_plain/09190394388163ef7df51c76bb33077ec8fc0949..49fa0d574a20817712006d479549dd96ccfff652:/linpy/linexprs.py diff --git a/linpy/linexprs.py b/linpy/linexprs.py index fce77a6..38fa7a1 100644 --- a/linpy/linexprs.py +++ b/linpy/linexprs.py @@ -411,7 +411,7 @@ class LinExpr: @classmethod def fromsympy(cls, expr): """ - Create a linear expression from a sympy expression. Raise ValueError is + Create a linear expression from a sympy expression. Raise TypeError is the sympy expression is not linear. """ import sympy @@ -421,12 +421,18 @@ class LinExpr: coefficient = Fraction(coefficient.p, coefficient.q) if symbol == sympy.S.One: constant = coefficient + elif isinstance(symbol, sympy.Dummy): + # we cannot properly convert dummy symbols + raise TypeError('cannot convert dummy symbols') elif isinstance(symbol, sympy.Symbol): symbol = Symbol(symbol.name) coefficients.append((symbol, coefficient)) else: - raise ValueError('non-linear expression: {!r}'.format(expr)) - return LinExpr(coefficients, constant) + raise TypeError('non-linear expression: {!r}'.format(expr)) + expr = LinExpr(coefficients, constant) + if not isinstance(expr, cls): + raise TypeError('cannot convert to a {} instance'.format(cls.__name__)) + return expr def tosympy(self): """ @@ -507,16 +513,6 @@ class Symbol(LinExpr): def _repr_latex_(self): return '$${}$$'.format(self.name) - @classmethod - def fromsympy(cls, expr): - import sympy - if isinstance(expr, sympy.Dummy): - return Dummy(expr.name) - elif isinstance(expr, sympy.Symbol): - return Symbol(expr.name) - else: - raise TypeError('expr must be a sympy.Symbol instance') - def symbols(names): """ @@ -632,13 +628,3 @@ class Rational(LinExpr, Fraction): else: return '$$\\frac{{{}}}{{{}}}$$'.format(self.numerator, self.denominator) - - @classmethod - def fromsympy(cls, expr): - import sympy - if isinstance(expr, sympy.Rational): - return Rational(expr.p, expr.q) - elif isinstance(expr, numbers.Rational): - return Rational(expr) - else: - raise TypeError('expr must be a sympy.Rational instance')