X-Git-Url: https://scm.cri.ensmp.fr/git/linpy.git/blobdiff_plain/b0a30ee84ef3c6e9505a8f872a260db373fdb641..ead3c442d29f0c45989d165f34e27dd0eb7d87c4:/pypol/linexprs.py diff --git a/pypol/linexprs.py b/pypol/linexprs.py index 9ab5c86..d8b020d 100644 --- a/pypol/linexprs.py +++ b/pypol/linexprs.py @@ -3,6 +3,7 @@ import functools import numbers import re +from collections import OrderedDict from fractions import Fraction, gcd @@ -67,13 +68,14 @@ class Expression: raise TypeError('coefficients must be rational numbers ' 'or Constant instances') self._coefficients[symbol] = coefficient + self._coefficients = OrderedDict(sorted(self._coefficients.items())) if isinstance(constant, Constant): constant = constant.constant if not isinstance(constant, numbers.Rational): raise TypeError('constant must be a rational number ' 'or a Constant instance') self._constant = constant - self._symbols = tuple(sorted(self._coefficients)) + self._symbols = tuple(self._coefficients) self._dimension = len(self._symbols) return self @@ -90,8 +92,7 @@ class Expression: __getitem__ = coefficient def coefficients(self): - for symbol in self.symbols: - yield symbol, self.coefficient(symbol) + yield from self._coefficients.items() @property def constant(self): @@ -220,7 +221,7 @@ class Expression: return Gt(self, other) def __hash__(self): - return hash((tuple(sorted(self._coefficients.items())), self._constant)) + return hash((tuple(self.coefficients()), self._constant)) def _toint(self): lcm = functools.reduce(lambda a, b: a*b // gcd(a, b),