Cleaner implementation of Domain.__sub__()

[linpy.git] / linpy / domains.py

diff --git a/linpy/domains.py b/linpy/domains.py
index 238248b..9fdc7d5 100644 (file)
--- a/linpy/domains.py
+++ b/linpy/domains.py
@@ -15,13 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with LinPy.  If not, see <http://www.gnu.org/licenses/>.
 
 # You should have received a copy of the GNU General Public License
 # along with LinPy.  If not, see <http://www.gnu.org/licenses/>.
 

-"""
-Polyhedral domains
-
-This module provides classes and functions to deal with polyhedral
-domains, i.e. unions of polyhedra.
-"""
-

 import ast
 import functools
 import re
 import ast
 import functools
 import re


@@ -44,7 +37,11 @@ __all__ = [
 @functools.total_ordering
 class Domain(GeometricObject):
     """
 @functools.total_ordering
 class Domain(GeometricObject):
     """

-    This class represents polyhedral domains, i.e. unions of polyhedra.
+    A domain is a union of polyhedra. Unlike polyhedra, domains allow exact
+    computation of union and complementary operations.
+
+    A domain with a unique polyhedron is automatically subclassed as a
+    Polyhedron instance.

     """
 
     __slots__ = (
     """
 
     __slots__ = (


@@ -55,7 +52,27 @@ class Domain(GeometricObject):
 
     def __new__(cls, *polyhedra):
         """
 
     def __new__(cls, *polyhedra):
         """

-        Create and return a new domain from a string or a list of polyhedra.
+        Return a domain from a sequence of polyhedra.
+
+        >>> square = Polyhedron('0 <= x <= 2, 0 <= y <= 2')
+        >>> square2 = Polyhedron('2 <= x <= 4, 2 <= y <= 4')
+        >>> dom = Domain([square, square2])
+
+        It is also possible to build domains from polyhedra using arithmetic
+        operators Domain.__and__(), Domain.__or__() or functions And() and Or(),
+        using one of the following instructions:
+
+        >>> square = Polyhedron('0 <= x <= 2, 0 <= y <= 2')
+        >>> square2 = Polyhedron('2 <= x <= 4, 2 <= y <= 4')
+        >>> dom = square | square2
+        >>> dom = Or(square, square2)
+
+        Alternatively, a domain can be built from a string:
+
+        >>> dom = Domain('0 <= x <= 2, 0 <= y <= 2; 2 <= x <= 4, 2 <= y <= 4')
+
+        Finally, a domain can be built from a GeometricObject instance, calling
+        the GeometricObject.asdomain() method.

         """
         from .polyhedra import Polyhedron
         if len(polyhedra) == 1:
         """
         from .polyhedra import Polyhedron
         if len(polyhedra) == 1:


@@ -88,35 +105,28 @@ class Domain(GeometricObject):
     @property
     def polyhedra(self):
         """
     @property
     def polyhedra(self):
         """

-        The tuple of polyhedra which constitute the domain.
+        The tuple of polyhedra present in the domain.

         """
         return self._polyhedra
 
     @property
     def symbols(self):
         """
         """
         return self._polyhedra
 
     @property
     def symbols(self):
         """

-        The tuple of symbols present in the domain equations.
+        The tuple of symbols present in the domain equations, sorted according
+        to Symbol.sortkey().

         """
         return self._symbols
 
     @property
     def dimension(self):
         """
         """
         return self._symbols
 
     @property
     def dimension(self):
         """

-        The dimension of the domain, i.e. the number of symbols.
+        The dimension of the domain, i.e. the number of symbols present in it.

         """
         return self._dimension
 
         """
         return self._dimension
 

-    def make_disjoint(self):
-        """
-        Return an equivalent domain, whose polyhedra are disjoint.
-        """
-        islset = self._toislset(self.polyhedra, self.symbols)
-        islset = libisl.isl_set_make_disjoint(mainctx, islset)
-        return self._fromislset(islset, self.symbols)
-

     def isempty(self):
         """
     def isempty(self):
         """

-        Return True if the domain is empty.
+        Return True if the domain is empty, that is, equal to Empty.

         """
         islset = self._toislset(self.polyhedra, self.symbols)
         empty = bool(libisl.isl_set_is_empty(islset))
         """
         islset = self._toislset(self.polyhedra, self.symbols)
         empty = bool(libisl.isl_set_is_empty(islset))


@@ -131,7 +141,7 @@ class Domain(GeometricObject):
 
     def isuniverse(self):
         """
 
     def isuniverse(self):
         """

-        Return True if the domain is universal, i.e. with no constraint.
+        Return True if the domain is universal, that is, equal to Universe.

         """
         islset = self._toislset(self.polyhedra, self.symbols)
         universe = bool(libisl.isl_set_plain_is_universe(islset))
         """
         islset = self._toislset(self.polyhedra, self.symbols)
         universe = bool(libisl.isl_set_plain_is_universe(islset))


@@ -149,20 +159,24 @@ class Domain(GeometricObject):
 
     def __eq__(self, other):
         """
 
     def __eq__(self, other):
         """

-        Return True if the two domains are equal.
+        Return True if two domains are equal.

         """
         """

-        symbols = self._xsymbols([self, other])
-        islset1 = self._toislset(self.polyhedra, symbols)
-        islset2 = other._toislset(other.polyhedra, symbols)
-        equal = bool(libisl.isl_set_is_equal(islset1, islset2))
-        libisl.isl_set_free(islset1)
-        libisl.isl_set_free(islset2)
-        return equal
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = other._toislset(other.polyhedra, symbols)
+            equal = bool(libisl.isl_set_is_equal(islset1, islset2))
+            libisl.isl_set_free(islset1)
+            libisl.isl_set_free(islset2)
+            return equal
+        return NotImplemented

 
     def isdisjoint(self, other):
         """
         Return True if two domains have a null intersection.
         """
 
     def isdisjoint(self, other):
         """
         Return True if two domains have a null intersection.
         """

+        if not isinstance(other, Domain):
+            raise TypeError('other must be a Domain instance')

         symbols = self._xsymbols([self, other])
         islset1 = self._toislset(self.polyhedra, symbols)
         islset2 = self._toislset(other.polyhedra, symbols)
         symbols = self._xsymbols([self, other])
         islset1 = self._toislset(self.polyhedra, symbols)
         islset2 = self._toislset(other.polyhedra, symbols)


@@ -175,29 +189,33 @@ class Domain(GeometricObject):
         """
         Report whether another domain contains the domain.
         """
         """
         Report whether another domain contains the domain.
         """

-        symbols = self._xsymbols([self, other])
-        islset1 = self._toislset(self.polyhedra, symbols)
-        islset2 = self._toislset(other.polyhedra, symbols)
-        equal = bool(libisl.isl_set_is_subset(islset1, islset2))
-        libisl.isl_set_free(islset1)
-        libisl.isl_set_free(islset2)
-        return equal
+        return self < other

 
     def __le__(self, other):
 
     def __le__(self, other):

-        return self.issubset(other)
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = self._toislset(other.polyhedra, symbols)
+            equal = bool(libisl.isl_set_is_subset(islset1, islset2))
+            libisl.isl_set_free(islset1)
+            libisl.isl_set_free(islset2)
+            return equal
+        return NotImplemented

     __le__.__doc__ = issubset.__doc__
 
     def __lt__(self, other):
         """
         Report whether another domain is contained within the domain.
         """
     __le__.__doc__ = issubset.__doc__
 
     def __lt__(self, other):
         """
         Report whether another domain is contained within the domain.
         """

-        symbols = self._xsymbols([self, other])
-        islset1 = self._toislset(self.polyhedra, symbols)
-        islset2 = self._toislset(other.polyhedra, symbols)
-        equal = bool(libisl.isl_set_is_strict_subset(islset1, islset2))
-        libisl.isl_set_free(islset1)
-        libisl.isl_set_free(islset2)
-        return equal
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = self._toislset(other.polyhedra, symbols)
+            equal = bool(libisl.isl_set_is_strict_subset(islset1, islset2))
+            libisl.isl_set_free(islset1)
+            libisl.isl_set_free(islset2)
+            return equal
+        return NotImplemented

 
     def complement(self):
         """
 
     def complement(self):
         """


@@ -211,10 +229,18 @@ class Domain(GeometricObject):
         return self.complement()
     __invert__.__doc__ = complement.__doc__
 
         return self.complement()
     __invert__.__doc__ = complement.__doc__
 

+    def make_disjoint(self):
+        """
+        Return an equivalent domain, whose polyhedra are disjoint.
+        """
+        islset = self._toislset(self.polyhedra, self.symbols)
+        islset = libisl.isl_set_make_disjoint(mainctx, islset)
+        return self._fromislset(islset, self.symbols)
+

     def coalesce(self):
         """
         Simplify the representation of the domain by trying to combine pairs of
     def coalesce(self):
         """
         Simplify the representation of the domain by trying to combine pairs of

-        polyhedra into a single polyhedron.
+        polyhedra into a single polyhedron, and return the resulting domain.

         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_coalesce(islset)
         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_coalesce(islset)


@@ -223,7 +249,7 @@ class Domain(GeometricObject):
     def detect_equalities(self):
         """
         Simplify the representation of the domain by detecting implicit
     def detect_equalities(self):
         """
         Simplify the representation of the domain by detecting implicit

-        equalities.
+        equalities, and return the resulting domain.

         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_detect_equalities(islset)
         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_detect_equalities(islset)


@@ -231,16 +257,14 @@ class Domain(GeometricObject):
 
     def remove_redundancies(self):
         """
 
     def remove_redundancies(self):
         """

-        Remove redundant constraints in the domain.
+        Remove redundant constraints in the domain, and return the resulting
+        domain.

         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_remove_redundancies(islset)
         return self._fromislset(islset, self.symbols)
 
     def aspolyhedron(self):
         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_remove_redundancies(islset)
         return self._fromislset(islset, self.symbols)
 
     def aspolyhedron(self):

-        """
-        Return the polyhedral hull of the domain.
-        """

         from .polyhedra import Polyhedron
         islset = self._toislset(self.polyhedra, self.symbols)
         islbset = libisl.isl_set_polyhedral_hull(islset)
         from .polyhedra import Polyhedron
         islset = self._toislset(self.polyhedra, self.symbols)
         islbset = libisl.isl_set_polyhedral_hull(islset)


@@ -251,8 +275,13 @@ class Domain(GeometricObject):
 
     def project(self, symbols):
         """
 
     def project(self, symbols):
         """

-        Project out the symbols given in arguments.
+        Project out the sequence of symbols given in arguments, and return the
+        resulting domain.

         """
         """

+        symbols = list(symbols)
+        for symbol in symbols:
+            if not isinstance(symbol, Symbol):
+                raise TypeError('symbols must be Symbol instances')

         islset = self._toislset(self.polyhedra, self.symbols)
         n = 0
         for index, symbol in reversed(list(enumerate(self.symbols))):
         islset = self._toislset(self.polyhedra, self.symbols)
         n = 0
         for index, symbol in reversed(list(enumerate(self.symbols))):


@@ -269,7 +298,8 @@ class Domain(GeometricObject):
 
     def sample(self):
         """
 
     def sample(self):
         """

-        Return a sample of the domain.
+        Return a sample of the domain, as an integer instance of Point. If the
+        domain is empty, a ValueError exception is raised.

         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islpoint = libisl.isl_set_sample_point(islset)
         """
         islset = self._toislset(self.polyhedra, self.symbols)
         islpoint = libisl.isl_set_sample_point(islset)


@@ -287,54 +317,62 @@ class Domain(GeometricObject):
 
     def intersection(self, *others):
         """
 
     def intersection(self, *others):
         """

-        Return the intersection of two domains as a new domain.
+        Return the intersection of two or more domains as a new domain. As an
+        alternative, function And() can be used.

         """
         """

-        if len(others) == 0:
-            return self
-        symbols = self._xsymbols((self,) + others)
-        islset1 = self._toislset(self.polyhedra, symbols)
+        result = self

         for other in others:
         for other in others:

-            islset2 = other._toislset(other.polyhedra, symbols)
-            islset1 = libisl.isl_set_intersect(islset1, islset2)
-        return self._fromislset(islset1, symbols)
+            result &= other
+        return result

 
     def __and__(self, other):
 
     def __and__(self, other):

-        return self.intersection(other)
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = other._toislset(other.polyhedra, symbols)
+            islset = libisl.isl_set_intersect(islset1, islset2)
+            return self._fromislset(islset, symbols)
+        return NotImplemented

     __and__.__doc__ = intersection.__doc__
 
     def union(self, *others):
         """
     __and__.__doc__ = intersection.__doc__
 
     def union(self, *others):
         """

-        Return the union of two domains as a new domain.
+        Return the union of two or more domains as a new domain. As an
+        alternative, function Or() can be used.

         """
         """

-        if len(others) == 0:
-            return self
-        symbols = self._xsymbols((self,) + others)
-        islset1 = self._toislset(self.polyhedra, symbols)
+        result = self

         for other in others:
         for other in others:

-            islset2 = other._toislset(other.polyhedra, symbols)
-            islset1 = libisl.isl_set_union(islset1, islset2)
-        return self._fromislset(islset1, symbols)
+            result |= other
+        return result

 
     def __or__(self, other):
 
     def __or__(self, other):

-        return self.union(other)
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = other._toislset(other.polyhedra, symbols)
+            islset = libisl.isl_set_union(islset1, islset2)
+            return self._fromislset(islset, symbols)
+        return NotImplemented

     __or__.__doc__ = union.__doc__
 
     def __add__(self, other):
     __or__.__doc__ = union.__doc__
 
     def __add__(self, other):

-        return self.union(other)
+        return self | other

     __add__.__doc__ = union.__doc__
 
     def difference(self, other):
         """
         Return the difference of two domains as a new domain.
         """
     __add__.__doc__ = union.__doc__
 
     def difference(self, other):
         """
         Return the difference of two domains as a new domain.
         """

-        symbols = self._xsymbols([self, other])
-        islset1 = self._toislset(self.polyhedra, symbols)
-        islset2 = other._toislset(other.polyhedra, symbols)
-        islset = libisl.isl_set_subtract(islset1, islset2)
-        return self._fromislset(islset, symbols)
+        return self - other

 
     def __sub__(self, other):
 
     def __sub__(self, other):

-        return self.difference(other)
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = other._toislset(other.polyhedra, symbols)
+            islset = libisl.isl_set_subtract(islset1, islset2)
+            return self._fromislset(islset, symbols)
+        return NotImplemented

     __sub__.__doc__ = difference.__doc__
 
     def lexmin(self):
     __sub__.__doc__ = difference.__doc__
 
     def lexmin(self):


@@ -357,7 +395,8 @@ class Domain(GeometricObject):
 
     def vertices(self):
         """
 
     def vertices(self):
         """

-        Return the vertices of the domain.
+        Return the vertices of the domain, as a list of rational instances of
+        Point.

         """
         from .polyhedra import Polyhedron
         if not self.isbounded():
         """
         from .polyhedra import Polyhedron
         if not self.isbounded():


@@ -396,7 +435,9 @@ class Domain(GeometricObject):
 
     def points(self):
         """
 
     def points(self):
         """

-        Return the points with integer coordinates contained in the domain.
+        Return the integer points of a bounded domain, as a list of integer
+        instances of Point. If the domain is not bounded, a ValueError exception
+        is raised.

         """
         if not self.isbounded():
             raise ValueError('domain must be bounded')
         """
         if not self.isbounded():
             raise ValueError('domain must be bounded')


@@ -414,6 +455,15 @@ class Domain(GeometricObject):
             points.append(Point(coordinates))
         return points
 
             points.append(Point(coordinates))
         return points
 

+    def __contains__(self, point):
+        """
+        Return True if the point if contained within the domain.
+        """
+        for polyhedron in self.polyhedra:
+            if point in polyhedron:
+                return True
+        return False
+

     @classmethod
     def _polygon_inner_point(cls, points):
         symbols = points[0].symbols
     @classmethod
     def _polygon_inner_point(cls, points):
         symbols = points[0].symbols


@@ -467,7 +517,9 @@ class Domain(GeometricObject):
 
     def faces(self):
         """
 
     def faces(self):
         """

-        Return the vertices of the domain, grouped by face.
+        Return the list of faces of a bounded domain. Each face is represented
+        by a list of vertices, in the form of rational instances of Point. If
+        the domain is not bounded, a ValueError exception is raised.

         """
         faces = []
         for polyhedron in self.polyhedra:
         """
         faces = []
         for polyhedron in self.polyhedra:


@@ -531,7 +583,11 @@ class Domain(GeometricObject):
 
     def plot(self, plot=None, **kwargs):
         """
 
     def plot(self, plot=None, **kwargs):
         """

-        Plot the domain using matplotlib.
+        Plot a 2D or 3D domain using matplotlib. Draw it to the current plot
+        object if present, otherwise create a new one. options are keyword
+        arguments passed to the matplotlib drawing functions, they can be used
+        to set the drawing color for example. Raise ValueError is the domain is
+        not 2D or 3D.

         """
         if not self.isbounded():
             raise ValueError('domain must be bounded')
         """
         if not self.isbounded():
             raise ValueError('domain must be bounded')


@@ -542,19 +598,12 @@ class Domain(GeometricObject):
         else:
             raise ValueError('polyhedron must be 2 or 3-dimensional')
 
         else:
             raise ValueError('polyhedron must be 2 or 3-dimensional')
 

-    def __contains__(self, point):
-        """
-        Return True if point if contained within the domain.
-        """
-        for polyhedron in self.polyhedra:
-            if point in polyhedron:
-                return True
-        return False
-

     def subs(self, symbol, expression=None):
         """
     def subs(self, symbol, expression=None):
         """

-        Subsitute symbol by expression in equations and return the resulting
-        domain.
+        Substitute the given symbol by an expression in the domain constraints.
+        To perform multiple substitutions at once, pass a sequence or a
+        dictionary of (old, new) pairs to subs. The syntax of this function is
+        similar to LinExpr.subs().

         """
         polyhedra = [polyhedron.subs(symbol, expression)
             for polyhedron in self.polyhedra]
         """
         polyhedra = [polyhedron.subs(symbol, expression)
             for polyhedron in self.polyhedra]


@@ -648,7 +697,8 @@ class Domain(GeometricObject):
     @classmethod
     def fromstring(cls, string):
         """
     @classmethod
     def fromstring(cls, string):
         """

-        Convert a string into a domain.
+        Create a domain from a string. Raise SyntaxError if the string is not
+        properly formatted.

         """
         # remove curly brackets
         string = cls._RE_BRACES.sub(r'', string)
         """
         # remove curly brackets
         string = cls._RE_BRACES.sub(r'', string)


@@ -671,9 +721,6 @@ class Domain(GeometricObject):
         return cls._fromast(tree)
 
     def __repr__(self):
         return cls._fromast(tree)
 
     def __repr__(self):

-        """
-        Return repr(self).
-        """

         assert len(self.polyhedra) >= 2
         strings = [repr(polyhedron) for polyhedron in self.polyhedra]
         return 'Or({})'.format(', '.join(strings))
         assert len(self.polyhedra) >= 2
         strings = [repr(polyhedron) for polyhedron in self.polyhedra]
         return 'Or({})'.format(', '.join(strings))


@@ -687,7 +734,7 @@ class Domain(GeometricObject):
     @classmethod
     def fromsympy(cls, expr):
         """
     @classmethod
     def fromsympy(cls, expr):
         """

-        Convert a SymPy expression into a domain.
+        Create a domain from a sympy expression.

         """
         import sympy
         from .polyhedra import Lt, Le, Eq, Ne, Ge, Gt
         """
         import sympy
         from .polyhedra import Lt, Le, Eq, Ne, Ge, Gt


@@ -706,7 +753,7 @@ class Domain(GeometricObject):
 
     def tosympy(self):
         """
 
     def tosympy(self):
         """

-        Convert a domain into a SymPy expression.
+        Convert the domain to a sympy expression.

         """
         import sympy
         polyhedra = [polyhedron.tosympy() for polyhedron in polyhedra]
         """
         import sympy
         polyhedra = [polyhedron.tosympy() for polyhedron in polyhedra]


@@ -714,6 +761,9 @@ class Domain(GeometricObject):
 
 
 def And(*domains):
 
 
 def And(*domains):

+    """
+    Create the intersection domain of the domains given in arguments.
+    """

     if len(domains) == 0:
         from .polyhedra import Universe
         return Universe
     if len(domains) == 0:
         from .polyhedra import Universe
         return Universe


@@ -722,6 +772,9 @@ def And(*domains):
 And.__doc__ = Domain.intersection.__doc__
 
 def Or(*domains):
 And.__doc__ = Domain.intersection.__doc__
 
 def Or(*domains):

+    """
+    Create the union domain of the domains given in arguments.
+    """

     if len(domains) == 0:
         from .polyhedra import Empty
         return Empty
     if len(domains) == 0:
         from .polyhedra import Empty
         return Empty


@@ -730,5 +783,8 @@ def Or(*domains):
 Or.__doc__ = Domain.union.__doc__
 
 def Not(domain):
 Or.__doc__ = Domain.union.__doc__
 
 def Not(domain):

+    """
+    Create the complementary domain of the domain given in argument.
+    """

     return ~domain
 Not.__doc__ = Domain.complement.__doc__
     return ~domain
 Not.__doc__ = Domain.complement.__doc__