X-Git-Url: https://scm.cri.ensmp.fr/git/linpy.git/blobdiff_plain/4e408d8113221ec6ecbaabdeb24ba0710c5a417c..b4bd8f7aa081b9296c6089310d286c3b7359a5cc:/linpy/polyhedra.py diff --git a/linpy/polyhedra.py b/linpy/polyhedra.py index fb2b4a7..a720b74 100644 --- a/linpy/polyhedra.py +++ b/linpy/polyhedra.py @@ -144,6 +144,15 @@ class Polyhedron(Domain): def aspolyhedron(self): return self + def convex_union(self, *others): + """ + Return the convex union of two or more polyhedra. + """ + for other in others: + if not isinstance(other, Polyhedron): + raise TypeError('arguments must be Polyhedron instances') + return Polyhedron(self.union(*others)) + def __contains__(self, point): if not isinstance(point, Point): raise TypeError('point must be a Point instance') @@ -164,7 +173,11 @@ class Polyhedron(Domain): for inequality in self.inequalities] return Polyhedron(equalities, inequalities) - def _asinequalities(self): + def asinequalities(self): + """ + Express the polyhedron using inequalities, given as a list of + expressions greater or equal to 0. + """ inequalities = list(self.equalities) inequalities.extend([-expression for expression in self.equalities]) inequalities.extend(self.inequalities) @@ -178,9 +191,9 @@ class Polyhedron(Domain): used on large polyhedra. """ if not isinstance(other, Polyhedron): - raise ValueError('argument must be a Polyhedron instance') - inequalities1 = self._asinequalities() - inequalities2 = other._asinequalities() + raise TypeError('argument must be a Polyhedron instance') + inequalities1 = self.asinequalities() + inequalities2 = other.asinequalities() inequalities = [] for inequality1 in inequalities1: if other <= Polyhedron(inequalities=[inequality1]): @@ -351,63 +364,77 @@ class UniverseType(Polyhedron): Universe = UniverseType() -def _polymorphic(func): +def _pseudoconstructor(func): @functools.wraps(func) - def wrapper(left, right): - if not isinstance(left, LinExpr): - if isinstance(left, numbers.Rational): - left = Rational(left) - else: - raise TypeError('left must be a a rational number ' - 'or a linear expression') - if not isinstance(right, LinExpr): - if isinstance(right, numbers.Rational): - right = Rational(right) - else: - raise TypeError('right must be a a rational number ' - 'or a linear expression') - return func(left, right) + def wrapper(expr1, expr2, *exprs): + exprs = (expr1, expr2) + exprs + for expr in exprs: + if not isinstance(expr, LinExpr): + if isinstance(expr, numbers.Rational): + expr = Rational(expr) + else: + raise TypeError('arguments must be rational numbers ' + 'or linear expressions') + return func(*exprs) return wrapper -@_polymorphic -def Lt(left, right): +@_pseudoconstructor +def Lt(*exprs): """ Create the polyhedron with constraints expr1 < expr2 < expr3 ... """ - return Polyhedron([], [right - left - 1]) + inequalities = [] + for left, right in zip(exprs, exprs[1:]): + inequalities.append(right - left - 1) + return Polyhedron([], inequalities) -@_polymorphic -def Le(left, right): +@_pseudoconstructor +def Le(*exprs): """ Create the polyhedron with constraints expr1 <= expr2 <= expr3 ... """ - return Polyhedron([], [right - left]) + inequalities = [] + for left, right in zip(exprs, exprs[1:]): + inequalities.append(right - left) + return Polyhedron([], inequalities) -@_polymorphic -def Eq(left, right): +@_pseudoconstructor +def Eq(*exprs): """ Create the polyhedron with constraints expr1 == expr2 == expr3 ... """ - return Polyhedron([left - right], []) + equalities = [] + for left, right in zip(exprs, exprs[1:]): + equalities.append(left - right) + return Polyhedron(equalities, []) -@_polymorphic -def Ne(left, right): +@_pseudoconstructor +def Ne(*exprs): """ Create the domain such that expr1 != expr2 != expr3 ... The result is a - Domain, not a Polyhedron. + Domain object, not a Polyhedron. """ - return ~Eq(left, right) + domain = Universe + for left, right in zip(exprs, exprs[1:]): + domain &= ~Eq(left, right) + return domain -@_polymorphic -def Ge(left, right): +@_pseudoconstructor +def Ge(*exprs): """ Create the polyhedron with constraints expr1 >= expr2 >= expr3 ... """ - return Polyhedron([], [left - right]) + inequalities = [] + for left, right in zip(exprs, exprs[1:]): + inequalities.append(left - right) + return Polyhedron([], inequalities) -@_polymorphic -def Gt(left, right): +@_pseudoconstructor +def Gt(*exprs): """ Create the polyhedron with constraints expr1 > expr2 > expr3 ... """ - return Polyhedron([], [left - right - 1]) + inequalities = [] + for left, right in zip(exprs, exprs[1:]): + inequalities.append(left - right - 1) + return Polyhedron([], inequalities)