-
+import ctypes, ctypes.util
import functools
import numbers
from fractions import Fraction, gcd
+from . import isl
+from .isl import libisl
+
__all__ = [
- 'Expression',
- 'constant', 'symbol', 'symbols',
+ 'Expression', 'Constant', 'Symbol', 'symbols',
'eq', 'le', 'lt', 'ge', 'gt',
'Polyhedron',
'empty', 'universe'
]
+def _polymorphic_method(func):
+ @functools.wraps(func)
+ def wrapper(a, b):
+ if isinstance(b, Expression):
+ return func(a, b)
+ if isinstance(b, numbers.Rational):
+ b = Constant(b)
+ return func(a, b)
+ return NotImplemented
+ 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)
+ return func(a, b)
+ elif isinstance(a, Expression):
+ return func(a, b)
+ raise TypeError('arguments must be linear expressions')
+ return wrapper
+
+
+_main_ctx = isl.Context()
+
+
class Expression:
"""
This class implements linear expressions.
if constant:
raise TypeError('too many arguments')
return cls.fromstring(coefficients)
- self = super().__new__(cls)
- self._coefficients = {}
if isinstance(coefficients, dict):
coefficients = coefficients.items()
- if coefficients is not None:
- for symbol, coefficient in coefficients:
- if isinstance(symbol, Expression) and symbol.issymbol():
- symbol = str(symbol)
- elif not isinstance(symbol, str):
- raise TypeError('symbols must be strings')
- if not isinstance(coefficient, numbers.Rational):
- raise TypeError('coefficients must be rational numbers')
- if coefficient != 0:
- self._coefficients[symbol] = coefficient
+ if coefficients is None:
+ return Constant(constant)
+ coefficients = [(symbol, coefficient)
+ for symbol, coefficient in coefficients if coefficient != 0]
+ if len(coefficients) == 0:
+ return Constant(constant)
+ elif len(coefficients) == 1:
+ symbol, coefficient = coefficients[0]
+ if coefficient == 1:
+ return Symbol(symbol)
+ self = object().__new__(cls)
+ self._coefficients = {}
+ for symbol, coefficient in coefficients:
+ if isinstance(symbol, Symbol):
+ symbol = str(symbol)
+ elif not isinstance(symbol, str):
+ raise TypeError('symbols must be strings or Symbol instances')
+ if isinstance(coefficient, Constant):
+ coefficient = coefficient.constant
+ if not isinstance(coefficient, numbers.Rational):
+ raise TypeError('coefficients must be rational numbers or Constant instances')
+ self._coefficients[symbol] = coefficient
+ if isinstance(constant, Constant):
+ constant = constant.constant
if not isinstance(constant, numbers.Rational):
- raise TypeError('constant must be a rational number')
+ raise TypeError('constant must be a rational number or a Constant instance')
self._constant = constant
+ self._symbols = tuple(sorted(self._coefficients))
+ self._dimension = len(self._symbols)
return self
+ @classmethod
+ def fromstring(cls, string):
+ raise NotImplementedError
+
+ @property
def symbols(self):
- yield from sorted(self._coefficients)
+ return self._symbols
@property
def dimension(self):
- return len(list(self.symbols()))
+ return self._dimension
def coefficient(self, symbol):
- if isinstance(symbol, Expression) and symbol.issymbol():
+ if isinstance(symbol, Symbol):
symbol = str(symbol)
elif not isinstance(symbol, str):
- raise TypeError('symbol must be a string')
+ raise TypeError('symbol must be a string or a Symbol instance')
try:
return self._coefficients[symbol]
except KeyError:
__getitem__ = coefficient
def coefficients(self):
- for symbol in self.symbols():
+ for symbol in self.symbols:
yield symbol, self.coefficient(symbol)
@property
return self._constant
def isconstant(self):
- return len(self._coefficients) == 0
+ return False
def values(self):
- for symbol in self.symbols():
+ for symbol in self.symbols:
yield self.coefficient(symbol)
yield self.constant
+ @property
def symbol(self):
- if not self.issymbol():
- raise ValueError('not a symbol: {}'.format(self))
- for symbol in self.symbols():
- return symbol
+ raise ValueError('not a symbol: {}'.format(self))
def issymbol(self):
- return len(self._coefficients) == 1 and self._constant == 0
+ return False
def __bool__(self):
- return (not self.isconstant()) or bool(self.constant)
+ True
def __pos__(self):
return self
def __neg__(self):
return self * -1
- def _polymorphic(func):
- @functools.wraps(func)
- def wrapper(self, other):
- if isinstance(other, Expression):
- return func(self, other)
- if isinstance(other, numbers.Rational):
- other = Expression(constant=other)
- return func(self, other)
- return NotImplemented
- return wrapper
-
- @_polymorphic
+ @_polymorphic_method
def __add__(self, other):
coefficients = dict(self.coefficients())
for symbol, coefficient in other.coefficients():
__radd__ = __add__
- @_polymorphic
+ @_polymorphic_method
def __sub__(self, other):
coefficients = dict(self.coefficients())
for symbol, coefficient in other.coefficients():
constant = self.constant - other.constant
return Expression(coefficients, constant)
- __rsub__ = __sub__
+ def __rsub__(self, other):
+ return -(self - other)
- @_polymorphic
+ @_polymorphic_method
def __mul__(self, other):
if other.isconstant():
coefficients = dict(self.coefficients())
__rmul__ = __mul__
- @_polymorphic
+ @_polymorphic_method
def __truediv__(self, other):
if other.isconstant():
coefficients = dict(self.coefficients())
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)
def __str__(self):
string = ''
- symbols = sorted(self.symbols())
i = 0
- for symbol in symbols:
- coefficient = self[symbol]
+ for symbol in self.symbols:
+ coefficient = self.coefficient(symbol)
if coefficient == 1:
if i == 0:
string += symbol
elif constant < 0:
constant *= -1
string += ' - {}'.format(constant)
+ if string == '':
+ string = '0'
return string
def _parenstr(self, always=False):
string += '}}, {!r})'.format(self.constant)
return string
- @classmethod
- def fromstring(cls, string):
- raise NotImplementedError
-
- @_polymorphic
+ @_polymorphic_method
def __eq__(self, other):
# "normal" equality
# see http://docs.sympy.org/dev/tutorial/gotchas.html#equals-signs
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
+ @_polymorphic_method
def _eq(self, other):
- return Polyhedron(equalities=[(self - other)._canonify()])
+ return Polyhedron(equalities=[(self - other)._toint()])
- @_polymorphic
+ @_polymorphic_method
def __le__(self, other):
- return Polyhedron(inequalities=[(self - other)._canonify()])
+ return Polyhedron(inequalities=[(other - self)._toint()])
- @_polymorphic
+ @_polymorphic_method
def __lt__(self, other):
- return Polyhedron(inequalities=[(self - other)._canonify() + 1])
+ return Polyhedron(inequalities=[(other - self)._toint() - 1])
- @_polymorphic
+ @_polymorphic_method
def __ge__(self, other):
- return Polyhedron(inequalities=[(other - self)._canonify()])
+ return Polyhedron(inequalities=[(self - other)._toint()])
- @_polymorphic
+ @_polymorphic_method
def __gt__(self, other):
- return Polyhedron(inequalities=[(other - self)._canonify() + 1])
+ return Polyhedron(inequalities=[(self - other)._toint() - 1])
+
+
+class Constant(Expression):
+ def __new__(cls, numerator=0, denominator=None):
+ self = object().__new__(cls)
+ if denominator is None:
+ if isinstance(numerator, numbers.Rational):
+ self._constant = numerator
+ elif isinstance(numerator, Constant):
+ self._constant = numerator.constant
+ else:
+ raise TypeError('constant must be a rational number or a Constant instance')
+ else:
+ self._constant = Fraction(numerator, denominator)
+ self._coefficients = {}
+ self._symbols = ()
+ self._dimension = 0
+ return self
+
+ def isconstant(self):
+ return True
-def constant(numerator=0, denominator=None):
- return Expression(constant=Fraction(numerator, denominator))
+ def __bool__(self):
+ return bool(self.constant)
-def symbol(name):
- if not isinstance(name, str):
- raise TypeError('name must be a string')
- return Expression(coefficients={name: 1})
+ def __repr__(self):
+ return '{}({!r})'.format(self.__class__.__name__, self._constant)
+
+
+class Symbol(Expression):
+
+ def __new__(cls, name):
+ if isinstance(name, Symbol):
+ name = name.symbol
+ elif not isinstance(name, str):
+ raise TypeError('name must be a string or a Symbol instance')
+ self = object().__new__(cls)
+ self._coefficients = {name: 1}
+ self._constant = 0
+ self._symbols = tuple(name)
+ self._symbol = name
+ self._dimension = 1
+ return self
+
+ @property
+ def symbol(self):
+ return self._symbol
+
+ def issymbol(self):
+ return True
+
+ def __repr__(self):
+ return '{}({!r})'.format(self.__class__.__name__, self._symbol)
def symbols(names):
if isinstance(names, str):
return (symbol(name) for name in names)
-def _operator(func):
- @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)
- raise TypeError('arguments must be linear expressions')
- return wrapper
-
-@_operator
+@_polymorphic_operator
def eq(a, b):
return a._eq(b)
-@_operator
+@_polymorphic_operator
def le(a, b):
return a <= b
-@_operator
+@_polymorphic_operator
def lt(a, b):
return a < b
-@_operator
+@_polymorphic_operator
def ge(a, b):
return a >= b
-@_operator
+@_polymorphic_operator
def gt(a, b):
return a > b
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:
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
+ @classmethod
+ def fromstring(cls, string):
+ raise NotImplementedError
+
@property
def equalities(self):
- yield from self._equalities
+ return self._equalities
@property
def inequalities(self):
- yield from self._inequalities
+ return self._inequalities
+ @property
def constraints(self):
- yield from self.equalities
- yield from self.inequalities
+ return self._constraints
+ @property
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):
- return len(self.symbols())
+ return len(self.symbols)
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?
raise NotImplementedError
def isempty(self):
- return self == empty
+ bset = self._toisl()
+ return bool(libisl.isl_basic_set_is_empty(bset))
def isuniverse(self):
- return self == universe
+ raise NotImplementedError
def isdisjoint(self, other):
# return true if the polyhedron has no elements in common with other
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 '{}(equalities={!r}, inequalities={!r})' \
''.format(self.__class__.__name__, equalities, inequalities)
+ def _symbolunion(self, *others):
+ symbols = set(self.symbols)
+ for other in others:
+ symbols.update(other.symbols)
+ return sorted(symbols)
+
+ def _toisl(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
+
@classmethod
- def fromstring(cls, string):
+ def _fromisl(cls, bset):
raise NotImplementedError
-
-
-empty = le(1, 0)
-
-universe = Polyhedron()
+ equalities = ...
+ inequalities = ...
+ return cls(equalities, inequalities)
+ '''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 }' '''
+ #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._toisl()
+ print(bs)
+ print('empty ?', p.isempty())
+ print('empty ?', eq(0, 1).isempty())
projects / linpy.git / blobdiff