# 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
@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__ = (
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:
@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):
"""
- 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):
"""
- 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
- 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):
"""
- 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))
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))
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)
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
- 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)
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)
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):
- """
- 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)
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.
"""
islset = self._toislset(self.polyhedra, self.symbols)
n = 0
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)
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
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
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():
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')
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
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:
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')
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):
"""
- 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]
@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)
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))
@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
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]
def And(*domains):
+ """
+ Create the intersection domain of the domains given in arguments.
+ """
if len(domains) == 0:
from .polyhedra import Universe
return Universe
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
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__
projects / linpy.git / blobdiff