Methods Polyhedron.fromsympy(), Polyhedron.tosympy()

[linpy.git] / pypol / linear.py

diff --git a/pypol/linear.py b/pypol/linear.py
index 524b3cb..74b5477 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -5,8 +5,8 @@ import re
 
 from fractions import Fraction, gcd
 
 
 from fractions import Fraction, gcd
 

-from pypol import isl
-from pypol.isl import libisl
+from . import isl
+from .isl import libisl

 
 
 __all__ = [
 
 
 __all__ = [


@@ -54,7 +54,7 @@ class Expression:
         '_coefficients',
         '_constant',
         '_symbols',
         '_coefficients',
         '_constant',
         '_symbols',

-        '_dimension'
+        '_dimension',

     )
 
     def __new__(cls, coefficients=None, constant=0):
     )
 
     def __new__(cls, coefficients=None, constant=0):


@@ -97,8 +97,7 @@ class Expression:
 
     @classmethod
     def _fromast(cls, node):
 
     @classmethod
     def _fromast(cls, node):

-        if isinstance(node, ast.Module):
-            assert len(node.body) == 1
+        if isinstance(node, ast.Module) and len(node.body) == 1:

             return cls._fromast(node.body[0])
         elif isinstance(node, ast.Expr):
             return cls._fromast(node.value)
             return cls._fromast(node.body[0])
         elif isinstance(node, ast.Expr):
             return cls._fromast(node.value)


@@ -106,9 +105,8 @@ class Expression:
             return Symbol(node.id)
         elif isinstance(node, ast.Num):
             return Constant(node.n)
             return Symbol(node.id)
         elif isinstance(node, ast.Num):
             return Constant(node.n)

-        elif isinstance(node, ast.UnaryOp):
-            if isinstance(node.op, ast.USub):
-                return -cls._fromast(node.operand)
+        elif isinstance(node, ast.UnaryOp) and isinstance(node.op, ast.USub):
+            return -cls._fromast(node.operand)

         elif isinstance(node, ast.BinOp):
             left = cls._fromast(node.left)
             right = cls._fromast(node.right)
         elif isinstance(node, ast.BinOp):
             left = cls._fromast(node.left)
             right = cls._fromast(node.right)


@@ -331,6 +329,31 @@ class Expression:
     def __gt__(self, other):
         return Polyhedron(inequalities=[(self - other)._toint() - 1])
 
     def __gt__(self, other):
         return Polyhedron(inequalities=[(self - other)._toint() - 1])
 

+    @classmethod
+    def fromsympy(cls, expr):
+        import sympy
+        coefficients = {}
+        constant = 0
+        for symbol, coefficient in expr.as_coefficients_dict().items():
+            coefficient = Fraction(coefficient.p, coefficient.q)
+            if symbol == sympy.S.One:
+                constant = coefficient
+            elif isinstance(symbol, sympy.Symbol):
+                symbol = symbol.name
+                coefficients[symbol] = coefficient
+            else:
+                raise ValueError('non-linear expression: {!r}'.format(expr))
+        return cls(coefficients, constant)
+
+    def tosympy(self):
+        import sympy
+        expr = 0
+        for symbol, coefficient in self.coefficients():
+            term = coefficient * sympy.Symbol(symbol)
+            expr += term
+        expr += self.constant
+        return expr
+

 
 class Constant(Expression):
 
 
 class Constant(Expression):
 


@@ -357,11 +380,29 @@ class Constant(Expression):
         return bool(self.constant)
 
     def __repr__(self):
         return bool(self.constant)
 
     def __repr__(self):

-        return '{}({!r})'.format(self.__class__.__name__, self._constant)
+        if self.constant.denominator == 1:
+            return '{}({!r})'.format(self.__class__.__name__, self.constant)
+        else:
+            return '{}({!r}, {!r})'.format(self.__class__.__name__,
+                self.constant.numerator, self.constant.denominator)
+
+    @classmethod
+    def fromsympy(cls, expr):
+        import sympy
+        if isinstance(expr, sympy.Rational):
+            return cls(expr.p, expr.q)
+        elif isinstance(expr, numbers.Rational):
+            return cls(expr)
+        else:
+            raise TypeError('expr must be a sympy.Rational instance')

 
 
 class Symbol(Expression):
 
 
 
 class Symbol(Expression):
 

+    __slots__ = Expression.__slots__ + (
+        '_name',
+    )
+

     def __new__(cls, name):
         if isinstance(name, Symbol):
             name = name.name
     def __new__(cls, name):
         if isinstance(name, Symbol):
             name = name.name


@@ -385,6 +426,15 @@ class Symbol(Expression):
     def __repr__(self):
         return '{}({!r})'.format(self.__class__.__name__, self._name)
 
     def __repr__(self):
         return '{}({!r})'.format(self.__class__.__name__, self._name)
 

+    @classmethod
+    def fromsympy(cls, expr):
+        import sympy
+        if isinstance(expr, sympy.Symbol):
+            return cls(expr.name)
+        else:
+            raise TypeError('expr must be a sympy.Symbol instance')
+
+

 def symbols(names):
     if isinstance(names, str):
         names = names.replace(',', ' ').split()
 def symbols(names):
     if isinstance(names, str):
         names = names.replace(',', ' ').split()


@@ -421,7 +471,7 @@ class Polyhedron:
         '_equalities',
         '_inequalities',
         '_constraints',
         '_equalities',
         '_inequalities',
         '_constraints',

-        '_symbols'
+        '_symbols',

     )
 
     def __new__(cls, equalities=None, inequalities=None):
     )
 
     def __new__(cls, equalities=None, inequalities=None):


@@ -456,23 +506,20 @@ class Polyhedron:
         return self
 
     @classmethod
         return self
 
     @classmethod

-    def fromstring(cls, string):
-        string = string.strip()
-        string = re.sub(r'^\{\s*|\s*\}$', '', string)
-        string = re.sub(r'([^<=>])=([^<=>])', r'\1==\2', string)
-        string = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()', r'\1*\2', string)
-        equalities = []
-        inequalities = []
-        for cstr in re.split(r',|;|and|&&|/\\|∧', string, flags=re.I):
-            tree = ast.parse(cstr.strip(), 'eval')
-            if not isinstance(tree, ast.Module) or len(tree.body) != 1:
-                raise SyntaxError('invalid syntax')
-            node = tree.body[0]
-            if not isinstance(node, ast.Expr):
-                raise SyntaxError('invalid syntax')
-            node = node.value
-            if not isinstance(node, ast.Compare):
-                raise SyntaxError('invalid syntax')
+    def _fromast(cls, node):
+        if isinstance(node, ast.Module) and len(node.body) == 1:
+            return cls._fromast(node.body[0])
+        elif isinstance(node, ast.Expr):
+            return cls._fromast(node.value)
+        elif isinstance(node, ast.BinOp) and isinstance(node.op, ast.BitAnd):
+            equalities1, inequalities1 = cls._fromast(node.left)
+            equalities2, inequalities2 = cls._fromast(node.right)
+            equalities = equalities1 + equalities2
+            inequalities = inequalities1 + inequalities2
+            return equalities, inequalities
+        elif isinstance(node, ast.Compare):
+            equalities = []
+            inequalities = []

             left = Expression._fromast(node.left)
             for i in range(len(node.ops)):
                 op = node.ops[i]
             left = Expression._fromast(node.left)
             for i in range(len(node.ops)):
                 op = node.ops[i]


@@ -488,8 +535,23 @@ class Polyhedron:
                 elif isinstance(op, ast.Gt):
                     inequalities.append(left - right - 1)
                 else:
                 elif isinstance(op, ast.Gt):
                     inequalities.append(left - right - 1)
                 else:

-                    raise SyntaxError('invalid syntax')
+                    break

                 left = right
                 left = right

+            else:
+                return equalities, inequalities
+        raise SyntaxError('invalid syntax')
+
+    @classmethod
+    def fromstring(cls, string):
+        string = string.strip()
+        string = re.sub(r'^\{\s*|\s*\}$', '', string)
+        string = re.sub(r'([^<=>])=([^<=>])', r'\1==\2', string)
+        string = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()', r'\1*\2', string)
+        tokens = re.split(r',|;|and|&&|/\\|∧', string, flags=re.I)
+        tokens = ['({})'.format(token) for token in tokens]
+        string = ' & '.join(tokens)
+        tree = ast.parse(string, 'eval')
+        equalities, inequalities = cls._fromast(tree)

         return cls(equalities, inequalities)
 
     @property
         return cls(equalities, inequalities)
 
     @property


@@ -624,6 +686,48 @@ class Polyhedron:
             return '{}(equalities={!r}, inequalities={!r})' \
                     ''.format(self.__class__.__name__, equalities, inequalities)
 
             return '{}(equalities={!r}, inequalities={!r})' \
                     ''.format(self.__class__.__name__, equalities, inequalities)
 

+    @classmethod
+    def _fromsympy(cls, expr):
+        import sympy
+        equalities = []
+        inequalities = []
+        if expr.func == sympy.And:
+            for arg in expr.args:
+                arg_eqs, arg_ins = cls._fromsympy(arg)
+                equalities.extend(arg_eqs)
+                inequalities.extend(arg_ins)
+        elif expr.func == sympy.Eq:
+            expr = Expression.fromsympy(expr.args[0] - expr.args[1])
+            equalities.append(expr)
+        else:
+            if expr.func == sympy.Lt:
+                expr = Expression.fromsympy(expr.args[1] - expr.args[0] - 1)
+            elif expr.func == sympy.Le:
+                expr = Expression.fromsympy(expr.args[1] - expr.args[0])
+            elif expr.func == sympy.Ge:
+                expr = Expression.fromsympy(expr.args[0] - expr.args[1])
+            elif expr.func == sympy.Gt:
+                expr = Expression.fromsympy(expr.args[0] - expr.args[1] - 1)
+            else:
+                raise ValueError('non-polyhedral expression: {!r}'.format(expr))
+            inequalities.append(expr)
+        return equalities, inequalities
+
+    @classmethod
+    def fromsympy(cls, expr):
+        import sympy
+        equalities, inequalities = cls._fromsympy(expr)
+        return cls(equalities, inequalities)
+
+    def tosympy(self):
+        import sympy
+        constraints = []
+        for equality in self.equalities:
+            constraints.append(sympy.Eq(equality.tosympy(), 0))
+        for inequality in self.inequalities:
+            constraints.append(sympy.Ge(inequality.tosympy(), 0))
+        return sympy.And(*constraints)
+

     def _symbolunion(self, *others):
         symbols = set(self.symbols)
         for other in others:
     def _symbolunion(self, *others):
         symbols = set(self.symbols)
         for other in others:


@@ -677,10 +781,13 @@ class Polyhedron:
             { [i0, i1] : 2i1 >= -2 - i0 } '''
 
 Empty = eq(0,1)
             { [i0, i1] : 2i1 >= -2 - i0 } '''
 
 Empty = eq(0,1)

+

 Universe = Polyhedron()
 
 Universe = Polyhedron()
 

+

 if __name__ == '__main__':
 if __name__ == '__main__':

-    p1 = Polyhedron('2a + 2b + 1 == 0') # empty
-    print(p1._toisl())
-    p2 = Polyhedron('3x + 2y + 3 == 0') # not empty
-    print(p2._toisl())
+    #p = Polyhedron('2a + 2b + 1 == 0') # empty
+    p = Polyhedron('3x + 2y + 3 == 0, y == 0') # not empty
+    ip = p._toisl()
+    print(ip)
+    print(ip.constraints())