X-Git-Url: https://svn.cri.ensmp.fr/git/linpy.git/blobdiff_plain/2a1055d4f4754fa33c53d3f155cc050e4911a2a3..960f0c252361dfd696359f803aae40a9b13b14a6:/pypol/polyhedra.py

diff --git a/pypol/polyhedra.py b/pypol/polyhedra.py
index a5048d1..9bfc64b 100644
--- a/pypol/polyhedra.py
+++ b/pypol/polyhedra.py
@@ -1,3 +1,20 @@
+# Copyright 2014 MINES ParisTech
+#
+# This file is part of Linpy.
+#
+# Linpy is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Linpy is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Linpy.  If not, see <http://www.gnu.org/licenses/>.
+
 import functools
 import math
 import numbers
@@ -5,8 +22,8 @@ import numbers
 from . import islhelper
 
 from .islhelper import mainctx, libisl
-from .geometry import GeometricObject, Point, Vector
-from .linexprs import Expression, Symbol, Rational
+from .geometry import GeometricObject, Point
+from .linexprs import Expression, Rational
 from .domains import Domain
 
 
@@ -56,14 +73,23 @@ class Polyhedron(Domain):
 
     @property
     def equalities(self):
+        """
+        Return a list of the equalities in a set.
+        """
         return self._equalities
 
     @property
     def inequalities(self):
+        """
+        Return a list of the inequalities in a set.
+        """
         return self._inequalities
 
     @property
     def constraints(self):
+        """
+        Return ta list of the constraints of a set.
+        """
         return self._constraints
 
     @property
@@ -72,13 +98,13 @@ class Polyhedron(Domain):
 
     def disjoint(self):
         """
-        Return this set as disjoint.
+        Return a set as disjoint.
         """
         return self
 
     def isuniverse(self):
         """
-        Return true if this set is the Universe set.
+        Return true if a set is the Universe set.
         """
         islbset = self._toislbasicset(self.equalities, self.inequalities,
             self.symbols)
@@ -88,7 +114,7 @@ class Polyhedron(Domain):
 
     def aspolyhedron(self):
         """
-        Return polyhedral hull of this set.
+        Return polyhedral hull of a set.
         """
         return self
 
@@ -106,12 +132,41 @@ class Polyhedron(Domain):
         return True
 
     def subs(self, symbol, expression=None):
+        """
+        Subsitute the given value into an expression and return the resulting
+        expression.
+        """
         equalities = [equality.subs(symbol, expression)
             for equality in self.equalities]
         inequalities = [inequality.subs(symbol, expression)
             for inequality in self.inequalities]
         return Polyhedron(equalities, inequalities)
 
+    def _asinequalities(self):
+        inequalities = list(self.equalities)
+        inequalities.extend([-expression for expression in self.equalities])
+        inequalities.extend(self.inequalities)
+        return inequalities
+
+    def widen(self, other):
+        if not isinstance(other, Polyhedron):
+            raise ValueError('argument must be a Polyhedron instance')
+        inequalities1 = self._asinequalities()
+        inequalities2 = other._asinequalities()
+        inequalities = []
+        for inequality1 in inequalities1:
+            if other <= Polyhedron(inequalities=[inequality1]):
+                inequalities.append(inequality1)
+        for inequality2 in inequalities2:
+            for i in range(len(inequalities1)):
+                inequalities3 = inequalities1[:i] + inequalities[i + 1:]
+                inequalities3.append(inequality2)
+                polyhedron3 = Polyhedron(inequalities=inequalities3)
+                if self == polyhedron3:
+                    inequalities.append(inequality2)
+                    break
+        return Polyhedron(inequalities=inequalities)
+
     @classmethod
     def _fromislbasicset(cls, islbset, symbols):
         islconstraints = islhelper.isl_basic_set_constraints(islbset)
@@ -184,42 +239,39 @@ class Polyhedron(Domain):
         return domain
 
     def __repr__(self):
-        if self.isempty():
-            return 'Empty'
-        elif self.isuniverse():
-            return 'Universe'
+        strings = []
+        for equality in self.equalities:
+            strings.append('Eq({}, 0)'.format(equality))
+        for inequality in self.inequalities:
+            strings.append('Ge({}, 0)'.format(inequality))
+        if len(strings) == 1:
+            return strings[0]
         else:
-            strings = []
-            for equality in self.equalities:
-                strings.append('Eq({}, 0)'.format(equality))
-            for inequality in self.inequalities:
-                strings.append('Ge({}, 0)'.format(inequality))
-            if len(strings) == 1:
-                return strings[0]
-            else:
-                return 'And({})'.format(', '.join(strings))
+            return 'And({})'.format(', '.join(strings))
+
 
     def _repr_latex_(self):
-        if self.isempty():
-            return '$\\emptyset$'
-        elif self.isuniverse():
-            return '$\\Omega$'
-        else:
-            strings = []
-            for equality in self.equalities:
-                strings.append('{} = 0'.format(equality._repr_latex_().strip('$')))
-            for inequality in self.inequalities:
-                strings.append('{} \\ge 0'.format(inequality._repr_latex_().strip('$')))
-            return '${}$'.format(' \\wedge '.join(strings))
+        strings = []
+        for equality in self.equalities:
+            strings.append('{} = 0'.format(equality._repr_latex_().strip('$')))
+        for inequality in self.inequalities:
+            strings.append('{} \\ge 0'.format(inequality._repr_latex_().strip('$')))
+        return '$${}$$'.format(' \\wedge '.join(strings))
 
     @classmethod
     def fromsympy(cls, expr):
+        """
+        Convert a sympy object to an expression.
+        """
         domain = Domain.fromsympy(expr)
         if not isinstance(domain, Polyhedron):
             raise ValueError('non-polyhedral expression: {!r}'.format(expr))
         return domain
 
     def tosympy(self):
+        """
+        Return an expression as a sympy object.
+        """
         import sympy
         constraints = []
         for equality in self.equalities:
@@ -228,127 +280,54 @@ class Polyhedron(Domain):
             constraints.append(sympy.Ge(inequality.tosympy(), 0))
         return sympy.And(*constraints)
 
-    @classmethod
-    def _polygon_inner_point(cls, points):
-        symbols = points[0].symbols
-        coordinates = {symbol: 0 for symbol in symbols}
-        for point in points:
-            for symbol, coordinate in point.coordinates():
-                coordinates[symbol] += coordinate
-        for symbol in symbols:
-            coordinates[symbol] /= len(points)
-        return Point(coordinates)
 
-    @classmethod
-    def _sort_polygon_2d(cls, points):
-        if len(points) <= 3:
-            return points
-        o = cls._polygon_inner_point(points)
-        angles = {}
-        for m in points:
-            om = Vector(o, m)
-            dx, dy = (coordinate for symbol, coordinate in om.coordinates())
-            angle = math.atan2(dy, dx)
-            angles[m] = angle
-        return sorted(points, key=angles.get)
+class EmptyType(Polyhedron):
+
+    __slots__ = Polyhedron.__slots__
+
+    def __new__(cls):
+        self = object().__new__(cls)
+        self._equalities = (Rational(1),)
+        self._inequalities = ()
+        self._constraints = self._equalities
+        self._symbols = ()
+        self._dimension = 0
+        return self
+
+    def widen(self, other):
+        if not isinstance(other, Polyhedron):
+            raise ValueError('argument must be a Polyhedron instance')
+        return other
+
+    def __repr__(self):
+        return 'Empty'
+
+    def _repr_latex_(self):
+        return '$$\\emptyset$$'
+
+Empty = EmptyType()
 
-    @classmethod
-    def _sort_polygon_3d(cls, points):
-        if len(points) <= 3:
-            return points
-        o = cls._polygon_inner_point(points)
-        a = points[0]
-        oa = Vector(o, a)
-        norm_oa = oa.norm()
-        for b in points[1:]:
-            ob = Vector(o, b)
-            u = oa.cross(ob)
-            if not u.isnull():
-                u = u.asunit()
-                break
-        else:
-            raise ValueError('degenerate polygon')
-        angles = {a: 0.}
-        for m in points[1:]:
-            om = Vector(o, m)
-            normprod = norm_oa * om.norm()
-            cosinus = max(oa.dot(om) / normprod, -1.)
-            sinus = u.dot(oa.cross(om)) / normprod
-            angle = math.acos(cosinus)
-            angle = math.copysign(angle, sinus)
-            angles[m] = angle
-        return sorted(points, key=angles.get)
-
-    def faces(self):
-        vertices = self.vertices()
-        faces = []
-        for constraint in self.constraints:
-            face = []
-            for vertex in vertices:
-                if constraint.subs(vertex.coordinates()) == 0:
-                    face.append(vertex)
-            faces.append(face)
-        return faces
-
-    def _plot_2d(self, plot=None, **kwargs):
-        from matplotlib import pylab
-        import matplotlib.pyplot as plt
-        from matplotlib.axes import Axes
-        from matplotlib.patches import Polygon
-        vertices = self._sort_polygon_2d(self.vertices())
-        xys = [tuple(vertex.values()) for vertex in vertices]
-        if plot is None:
-            fig = plt.figure()
-            plot = fig.add_subplot(1, 1, 1)
-            xs, ys = zip(*xys)
-            plot.set_xlim(float(min(xs)), float(max(xs)))
-            plot.set_ylim(float(min(ys)), float(max(ys)))
-        plot.add_patch(Polygon(xys, closed=True, **kwargs))
-        return plot
-
-    def _plot_3d(self, plot=None, **kwargs):
-        import matplotlib.pyplot as plt
-        from mpl_toolkits.mplot3d import Axes3D
-        from mpl_toolkits.mplot3d.art3d import Poly3DCollection
-        if plot is None:
-            fig = plt.figure()
-            axes = Axes3D(fig)
-            xmin, xmax = float('inf'), float('-inf')
-            ymin, ymax = float('inf'), float('-inf')
-            zmin, zmax = float('inf'), float('-inf')
-        else:
-            axes = plot
-        poly_xyzs = []
-        for vertices in self.faces():
-            if len(vertices) == 0:
-                continue
-            vertices = Polyhedron._sort_polygon_3d(vertices)
-            vertices.append(vertices[0])
-            face_xyzs = [tuple(vertex.values()) for vertex in vertices]
-            if plot is None:
-                xs, ys, zs = zip(*face_xyzs)
-                xmin, xmax = min(xmin, float(min(xs))), max(xmax, float(max(xs)))
-                ymin, ymax = min(ymin, float(min(ys))), max(ymax, float(max(ys)))
-                zmin, zmax = min(zmin, float(min(zs))), max(zmax, float(max(zs)))
-            poly_xyzs.append(face_xyzs)
-        collection = Poly3DCollection(poly_xyzs, **kwargs)
-        axes.add_collection3d(collection)
-        if plot is None:
-            axes.set_xlim(xmin, xmax)
-            axes.set_ylim(ymin, ymax)
-            axes.set_zlim(zmin, zmax)
-        return axes
-
-    def plot(self, plot=None, **kwargs):
-        """
-        Display 3D plot of set.
-        """
-        if self.dimension == 2:
-            return self._plot_2d(plot=plot, **kwargs)
-        elif self.dimension == 3:
-            return self._plot_3d(plot=plot, **kwargs)
-        else:
-            raise ValueError('polyhedron must be 2 or 3-dimensional')
+
+class UniverseType(Polyhedron):
+
+    __slots__ = Polyhedron.__slots__
+
+    def __new__(cls):
+        self = object().__new__(cls)
+        self._equalities = ()
+        self._inequalities = ()
+        self._constraints = ()
+        self._symbols = ()
+        self._dimension = ()
+        return self
+
+    def __repr__(self):
+        return 'Universe'
+
+    def _repr_latex_(self):
+        return '$$\\Omega$$'
+
+Universe = UniverseType()
 
 
 def _polymorphic(func):
@@ -372,46 +351,41 @@ def _polymorphic(func):
 @_polymorphic
 def Lt(left, right):
     """
-    Return true if the first set is less than the second.
+    Assert first set is less than the second set.
     """
     return Polyhedron([], [right - left - 1])
 
 @_polymorphic
 def Le(left, right):
     """
-    Return true the first set is less than or equal to the second.
+    Assert first set is less than or equal to the second set.
     """
     return Polyhedron([], [right - left])
 
 @_polymorphic
 def Eq(left, right):
     """
-    Return true if the sets are equal.
+    Assert first set is equal to the second set.
     """
     return Polyhedron([left - right], [])
 
 @_polymorphic
 def Ne(left, right):
     """
-    Return true if the sets are NOT equal.
+    Assert first set is not equal to the second set.
     """
     return ~Eq(left, right)
 
 @_polymorphic
 def Gt(left, right):
     """
-    Return true if the first set is greater than the second set.
+    Assert first set is greater than the second set.
     """
     return Polyhedron([], [left - right - 1])
 
 @_polymorphic
 def Ge(left, right):
     """
-    Return true if the first set is greater than or equal the second set.
+    Assert first set is greater than or equal to the second set.
     """
     return Polyhedron([], [left - right])
-
-
-Empty = Eq(1, 0)
-
-Universe = Polyhedron([])