Document function And() before Or()

[linpy.git] / linpy / polyhedra.py

diff --git a/linpy/polyhedra.py b/linpy/polyhedra.py
index 543e673..b88cfd1 100644 (file)
--- a/linpy/polyhedra.py
+++ b/linpy/polyhedra.py
@@ -87,22 +87,20 @@ class Polyhedron(Domain):
             if inequalities is not None:
                 raise TypeError('too many arguments')
             return equalities.aspolyhedron()
             if inequalities is not None:
                 raise TypeError('too many arguments')
             return equalities.aspolyhedron()

-        if equalities is None:
-            equalities = []
-        else:
-            for i, equality in enumerate(equalities):
+        sc_equalities = []
+        if equalities is not None:
+            for equality in equalities:

                 if not isinstance(equality, LinExpr):
                     raise TypeError('equalities must be linear expressions')
                 if not isinstance(equality, LinExpr):
                     raise TypeError('equalities must be linear expressions')

-                equalities[i] = equality.scaleint()
-        if inequalities is None:
-            inequalities = []
-        else:
-            for i, inequality in enumerate(inequalities):
+                sc_equalities.append(equality.scaleint())
+        sc_inequalities = []
+        if inequalities is not None:
+            for inequality in inequalities:

                 if not isinstance(inequality, LinExpr):
                     raise TypeError('inequalities must be linear expressions')
                 if not isinstance(inequality, LinExpr):
                     raise TypeError('inequalities must be linear expressions')

-                inequalities[i] = inequality.scaleint()
-        symbols = cls._xsymbols(equalities + inequalities)
-        islbset = cls._toislbasicset(equalities, inequalities, symbols)
+                sc_inequalities.append(inequality.scaleint())
+        symbols = cls._xsymbols(sc_equalities + sc_inequalities)
+        islbset = cls._toislbasicset(sc_equalities, sc_inequalities, symbols)

         return cls._fromislbasicset(islbset, symbols)
 
     @property
         return cls._fromislbasicset(islbset, symbols)
 
     @property


@@ -146,6 +144,15 @@ class Polyhedron(Domain):
     def aspolyhedron(self):
         return self
 
     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')
     def __contains__(self, point):
         if not isinstance(point, Point):
             raise TypeError('point must be a Point instance')


@@ -166,7 +173,11 @@ class Polyhedron(Domain):
             for inequality in self.inequalities]
         return Polyhedron(equalities, inequalities)
 
             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)
         inequalities = list(self.equalities)
         inequalities.extend([-expression for expression in self.equalities])
         inequalities.extend(self.inequalities)


@@ -175,11 +186,14 @@ class Polyhedron(Domain):
     def widen(self, other):
         """
         Compute the standard widening of two polyhedra, à la Halbwachs.
     def widen(self, other):
         """
         Compute the standard widening of two polyhedra, à la Halbwachs.

+
+        In its current implementation, this method is slow and should not be
+        used on large polyhedra.

         """
         if not isinstance(other, Polyhedron):
         """
         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]):
         inequalities = []
         for inequality1 in inequalities1:
             if other <= Polyhedron(inequalities=[inequality1]):


@@ -305,8 +319,6 @@ class EmptyType(Polyhedron):
     The empty polyhedron, whose set of constraints is not satisfiable.
     """
 
     The empty polyhedron, whose set of constraints is not satisfiable.
     """
 

-    __slots__ = Polyhedron.__slots__
-

     def __new__(cls):
         self = object().__new__(cls)
         self._equalities = (Rational(1),)
     def __new__(cls):
         self = object().__new__(cls)
         self._equalities = (Rational(1),)


@@ -335,8 +347,6 @@ class UniverseType(Polyhedron):
     i.e. is empty.
     """
 
     i.e. is empty.
     """
 

-    __slots__ = Polyhedron.__slots__
-

     def __new__(cls):
         self = object().__new__(cls)
         self._equalities = ()
     def __new__(cls):
         self = object().__new__(cls)
         self._equalities = ()


@@ -402,15 +412,15 @@ def Ne(left, right):
     return ~Eq(left, right)
 
 @_polymorphic
     return ~Eq(left, right)
 
 @_polymorphic

-def Gt(left, right):
+def Ge(left, right):

     """
     """

-    Create the polyhedron with constraints expr1 > expr2 > expr3 ...
+    Create the polyhedron with constraints expr1 >= expr2 >= expr3 ...

     """
     """

-    return Polyhedron([], [left - right - 1])
+    return Polyhedron([], [left - right])

 
 @_polymorphic
 
 @_polymorphic

-def Ge(left, right):
+def Gt(left, right):

     """
     """

-    Create the polyhedron with constraints expr1 >= expr2 >= expr3 ...
+    Create the polyhedron with constraints expr1 > expr2 > expr3 ...

     """
     """

-    return Polyhedron([], [left - right])
+    return Polyhedron([], [left - right - 1])