Fix Polyhedron.isempty()

[linpy.git] / pypol / linear.py

diff --git a/pypol/linear.py b/pypol/linear.py
index fabf2a2..5f3c559 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -1,9 +1,12 @@
-
+import ctypes, ctypes.util

 import functools
 import numbers
 
 from fractions import Fraction, gcd
 
 import functools
 import numbers
 
 from fractions import Fraction, gcd
 

+from . import isl
+from .isl import libisl
+

 
 __all__ = [
     'Expression',
 
 __all__ = [
     'Expression',


@@ -26,18 +29,22 @@ def _polymorphic_method(func):
     return wrapper
 
 def _polymorphic_operator(func):
     return wrapper
 
 def _polymorphic_operator(func):

+    # A polymorphic operator should call a polymorphic method, hence we just
+    # have to test the left operand.

     @functools.wraps(func)
     def wrapper(a, b):
         if isinstance(a, numbers.Rational):
             a = constant(a)
     @functools.wraps(func)
     def wrapper(a, b):
         if isinstance(a, numbers.Rational):
             a = constant(a)

-        if isinstance(b, numbers.Rational):
-            b = constant(b)
-        if isinstance(a, Expression) and isinstance(b, Expression):
+            return func(a, b)
+        elif isinstance(a, Expression):

             return func(a, b)
         raise TypeError('arguments must be linear expressions')
     return wrapper
 
 
             return func(a, b)
         raise TypeError('arguments must be linear expressions')
     return wrapper
 
 

+_main_ctx = isl.Context()
+
+

 class Expression:
     """
     This class implements linear expressions.
 class Expression:
     """
     This class implements linear expressions.


@@ -65,14 +72,17 @@ class Expression:
         if not isinstance(constant, numbers.Rational):
             raise TypeError('constant must be a rational number')
         self._constant = constant
         if not isinstance(constant, numbers.Rational):
             raise TypeError('constant must be a rational number')
         self._constant = constant

+        self._symbols = tuple(sorted(self._coefficients))
+        self._dimension = len(self._symbols)

         return self
 
         return self
 

+    @property

     def symbols(self):
     def symbols(self):

-        yield from sorted(self._coefficients)
+        return self._symbols

 
     @property
     def dimension(self):
 
     @property
     def dimension(self):

-        return len(list(self.symbols()))
+        return self._dimension

 
     def coefficient(self, symbol):
         if isinstance(symbol, Expression) and symbol.issymbol():
 
     def coefficient(self, symbol):
         if isinstance(symbol, Expression) and symbol.issymbol():


@@ -87,7 +97,7 @@ class Expression:
     __getitem__ = coefficient
 
     def coefficients(self):
     __getitem__ = coefficient
 
     def coefficients(self):

-        for symbol in self.symbols():
+        for symbol in self.symbols:

             yield symbol, self.coefficient(symbol)
 
     @property
             yield symbol, self.coefficient(symbol)
 
     @property


@@ -98,14 +108,20 @@ class Expression:
         return len(self._coefficients) == 0
 
     def values(self):
         return len(self._coefficients) == 0
 
     def values(self):

-        for symbol in self.symbols():
+        for symbol in self.symbols:

             yield self.coefficient(symbol)
         yield self.constant
 
             yield self.coefficient(symbol)
         yield self.constant
 

+    def values_int(self):
+        for symbol in self.symbols:
+            return self.coefficient(symbol)
+        return int(self.constant)
+
+    @property

     def symbol(self):
         if not self.issymbol():
             raise ValueError('not a symbol: {}'.format(self))
     def symbol(self):
         if not self.issymbol():
             raise ValueError('not a symbol: {}'.format(self))

-        for symbol in self.symbols():
+        for symbol in self.symbols:

             return symbol
 
     def issymbol(self):
             return symbol
 
     def issymbol(self):


@@ -144,7 +160,8 @@ class Expression:
         constant = self.constant - other.constant
         return Expression(coefficients, constant)
 
         constant = self.constant - other.constant
         return Expression(coefficients, constant)
 

-    __rsub__ = __sub__
+    def __rsub__(self, other):
+        return -(self - other)

 
     @_polymorphic_method
     def __mul__(self, other):
 
     @_polymorphic_method
     def __mul__(self, other):


@@ -176,7 +193,7 @@ class Expression:
         return NotImplemented
 
     def __rtruediv__(self, other):
         return NotImplemented
 
     def __rtruediv__(self, other):

-        if isinstance(other, Rational):
+        if isinstance(other, self):

             if self.isconstant():
                 constant = Fraction(other, self.constant)
                 return Expression(constant=constant)
             if self.isconstant():
                 constant = Fraction(other, self.constant)
                 return Expression(constant=constant)


@@ -187,7 +204,6 @@ class Expression:
 
     def __str__(self):
         string = ''
 
     def __str__(self):
         string = ''

-        symbols = sorted(self.symbols())

         i = 0
         for symbol in symbols:
             coefficient = self[symbol]
         i = 0
         for symbol in symbols:
             coefficient = self[symbol]


@@ -254,30 +270,30 @@ class Expression:
     def __hash__(self):
         return hash((self._coefficients, self._constant))
 
     def __hash__(self):
         return hash((self._coefficients, self._constant))
 

-    def _canonify(self):
+    def _toint(self):

         lcm = functools.reduce(lambda a, b: a*b // gcd(a, b),
                 [value.denominator for value in self.values()])
         return self * lcm
 
     @_polymorphic_method
     def _eq(self, other):
         lcm = functools.reduce(lambda a, b: a*b // gcd(a, b),
                 [value.denominator for value in self.values()])
         return self * lcm
 
     @_polymorphic_method
     def _eq(self, other):

-        return Polyhedron(equalities=[(self - other)._canonify()])
+        return Polyhedron(equalities=[(self - other)._toint()])

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

-        return Polyhedron(inequalities=[(self - other)._canonify()])
+        return Polyhedron(inequalities=[(other - self)._toint()])

 
     @_polymorphic_method
     def __lt__(self, other):
 
     @_polymorphic_method
     def __lt__(self, other):

-        return Polyhedron(inequalities=[(self - other)._canonify() + 1])
+        return Polyhedron(inequalities=[(other - self)._toint() - 1])

 
     @_polymorphic_method
     def __ge__(self, other):
 
     @_polymorphic_method
     def __ge__(self, other):

-        return Polyhedron(inequalities=[(other - self)._canonify()])
+        return Polyhedron(inequalities=[(self - other)._toint()])

 
     @_polymorphic_method
     def __gt__(self, other):
 
     @_polymorphic_method
     def __gt__(self, other):

-        return Polyhedron(inequalities=[(other - self)._canonify() + 1])
+        return Polyhedron(inequalities=[(self - other)._toint() - 1])

 
 
 def constant(numerator=0, denominator=None):
 
 
 def constant(numerator=0, denominator=None):


@@ -337,6 +353,7 @@ class Polyhedron:
                         raise TypeError('non-integer constraint: '
                                 '{} == 0'.format(constraint))
                 self._equalities.append(constraint)
                         raise TypeError('non-integer constraint: '
                                 '{} == 0'.format(constraint))
                 self._equalities.append(constraint)

+        self._equalities = tuple(self._equalities)

         self._inequalities = []
         if inequalities is not None:
             for constraint in inequalities:
         self._inequalities = []
         if inequalities is not None:
             for constraint in inequalities:


@@ -345,33 +362,36 @@ class Polyhedron:
                         raise TypeError('non-integer constraint: '
                                 '{} <= 0'.format(constraint))
                 self._inequalities.append(constraint)
                         raise TypeError('non-integer constraint: '
                                 '{} <= 0'.format(constraint))
                 self._inequalities.append(constraint)

+        self._inequalities = tuple(self._inequalities)
+        self._constraints = self._equalities + self._inequalities
+        self._symbols = set()
+        for constraint in self._constraints:
+            self.symbols.update(constraint.symbols)
+        self._symbols = tuple(sorted(self._symbols))

         return self
 
     @property
     def equalities(self):
         return self
 
     @property
     def equalities(self):

-        yield from self._equalities
+        return self._equalities

 
     @property
     def inequalities(self):
 
     @property
     def inequalities(self):

-        yield from self._inequalities
+        return self._inequalities

 
 

+    @property

     def constraints(self):
     def constraints(self):

-        yield from self.equalities
-        yield from self.inequalities
+        return self._constraints

 
 

+    @property

     def symbols(self):
     def symbols(self):

-        s = set()
-        for constraint in self.constraints():
-            s.update(constraint.symbols)
-        yield from sorted(s)
+        return self._symbols

 
     @property
     def dimension(self):
 
     @property
     def dimension(self):

-        return len(self.symbols())
+        return len(self.symbols)

 
     def __bool__(self):
 
     def __bool__(self):

-        # return false if the polyhedron is empty, true otherwise
-        raise NotImplementedError
+        return not self.is_empty()

 
     def __contains__(self, value):
         # is the value in the polyhedron?
 
     def __contains__(self, value):
         # is the value in the polyhedron?


@@ -381,10 +401,11 @@ class Polyhedron:
         raise NotImplementedError
 
     def isempty(self):
         raise NotImplementedError
 
     def isempty(self):

-        return self == empty
+        bset = self._to_isl()
+        return bool(libisl.isl_basic_set_is_empty(bset))

 
     def isuniverse(self):
 
     def isuniverse(self):

-        return self == universe
+        raise NotImplementedError

 
     def isdisjoint(self, other):
         # return true if the polyhedron has no elements in common with other
 
     def isdisjoint(self, other):
         # return true if the polyhedron has no elements in common with other


@@ -445,7 +466,7 @@ class Polyhedron:
         for constraint in self.equalities:
             constraints.append('{} == 0'.format(constraint))
         for constraint in self.inequalities:
         for constraint in self.equalities:
             constraints.append('{} == 0'.format(constraint))
         for constraint in self.inequalities:

-            constraints.append('{} <= 0'.format(constraint))
+            constraints.append('{} >= 0'.format(constraint))

         return '{{{}}}'.format(', '.join(constraints))
 
     def __repr__(self):
         return '{{{}}}'.format(', '.join(constraints))
 
     def __repr__(self):


@@ -458,7 +479,75 @@ class Polyhedron:
     def fromstring(cls, string):
         raise NotImplementedError
 
     def fromstring(cls, string):
         raise NotImplementedError
 

+    def _symbolunion(self, *others):
+        symbols = set(self.symbols)
+        for other in others:
+            symbols.update(other.symbols)
+        return sorted(symbols)
+
+    def _to_isl(self, symbols=None):
+        if symbols is None:
+            symbols = self.symbols
+        num_coefficients = len(symbols)
+        space = libisl.isl_space_set_alloc(_main_ctx, 0, num_coefficients)
+        bset = libisl.isl_basic_set_universe(libisl.isl_space_copy(space))
+        ls = libisl.isl_local_space_from_space(space)
+        ceq = libisl.isl_equality_alloc(libisl.isl_local_space_copy(ls))
+        cin = libisl.isl_inequality_alloc(libisl.isl_local_space_copy(ls))
+        '''if there are equalities/inequalities, take each constant and coefficient and add as a constraint to the basic set'''
+        if list(self.equalities): #check if any equalities exist
+            for eq in self.equalities:
+                coeff_eq = dict(eq.coefficients())
+                if eq.constant:
+                    value = eq.constant
+                    ceq = libisl.isl_constraint_set_constant_si(ceq, value)
+                for eq in coeff_eq:
+                    num = coeff_eq.get(eq)
+                    iden = symbols.index(eq)
+                    ceq = libisl.isl_constraint_set_coefficient_si(ceq, libisl.isl_dim_set, iden, num)  #use 3 for type isl_dim_set
+            bset = libisl.isl_basic_set_add_constraint(bset, ceq)
+        if list(self.inequalities): #check if any inequalities exist
+            for ineq in self.inequalities:
+                coeff_in = dict(ineq.coefficients())
+                if ineq.constant:
+                    value = ineq.constant
+                    cin = libisl.isl_constraint_set_constant_si(cin, value)
+                for ineq in coeff_in:
+                    num = coeff_in.get(ineq)
+                    iden = symbols.index(ineq)
+                    cin = libisl.isl_constraint_set_coefficient_si(cin, libisl.isl_dim_set, iden, num)  #use 3 for type isl_dim_set
+            bset = libisl.isl_basic_set_add_constraint(bset, cin)
+        bset = isl.BasicSet(bset)
+        return bset

 
 

-empty = le(1, 0)
-
-universe = Polyhedron()
+    @classmethod
+    def _from_isl(cls, bset):
+        '''takes basic set in isl form and puts back into python version of polyhedron
+        isl example code gives isl form as:
+            "{[i] : exists (a : i = 2a and i >= 10 and i <= 42)}")
+            our printer is giving form as:
+            b'{ [i0] : 1 = 0 }' '''
+        raise NotImplementedError
+        equalities = ...
+        inequalities = ...
+        return cls(equalities, inequalities)
+        #bset = self
+        # if self._equalities:
+        #     constraints = libisl.isl_basic_set_equalities_matrix(bset, 3)
+        # elif self._inequalities:
+        #     constraints = libisl.isl_basic_set_inequalities_matrix(bset, 3)
+        # print(constraints)
+        # return constraints
+
+empty = None #eq(0,1)
+universe = None #Polyhedron()
+
+
+if __name__ == '__main__':
+    ex1 = Expression(coefficients={'a': 1, 'x': 2}, constant=2)
+    ex2 = Expression(coefficients={'a': 3  , 'b': 2}, constant=3)
+    p = Polyhedron(inequalities=[ex1, ex2])
+    bs = p._to_isl()
+    print(bs)
+    print('empty ?', p.isempty())
+    print('empty ?', eq(0, 1).isempty())