Update reference examples to match the tutorial

[linpy.git] / linpy / linexprs.py

diff --git a/linpy/linexprs.py b/linpy/linexprs.py
index c100698..a0be583 100644 (file)
--- a/linpy/linexprs.py
+++ b/linpy/linexprs.py
@@ -247,26 +247,28 @@ class LinExpr:
         """
         Test whether two linear expressions are equal.
         """
         """
         Test whether two linear expressions are equal.
         """

-        if isinstance(other, LinExpr):
-            return self._coefficients == other._coefficients and \
-                self._constant == other._constant
-        return NotImplemented
-
-    def __le__(self, other):
-        from .polyhedra import Le
-        return Le(self, other)
+        return self._coefficients == other._coefficients and \
+            self._constant == other._constant

 
 

+    @_polymorphic

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

-        from .polyhedra import Lt
-        return Lt(self, other)
+        from .polyhedra import Polyhedron
+        return Polyhedron([], [other - self - 1])

 
 

+    @_polymorphic
+    def __le__(self, other):
+        from .polyhedra import Polyhedron
+        return Polyhedron([], [other - self])
+
+    @_polymorphic

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

-        from .polyhedra import Ge
-        return Ge(self, other)
+        from .polyhedra import Polyhedron
+        return Polyhedron([], [self - other])

 
 

+    @_polymorphic

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

-        from .polyhedra import Gt
-        return Gt(self, other)
+        from .polyhedra import Polyhedron
+        return Polyhedron([], [self - other - 1])

 
     def scaleint(self):
         """
 
     def scaleint(self):
         """


@@ -339,7 +341,7 @@ class LinExpr:
         Create an expression from a string. Raise SyntaxError if the string is
         not properly formatted.
         """
         Create an expression from a string. Raise SyntaxError if the string is
         not properly formatted.
         """

-        # add implicit multiplication operators, e.g. '5x' -> '5*x'
+        # Add implicit multiplication operators, e.g. '5x' -> '5*x'.

         string = LinExpr._RE_NUM_VAR.sub(r'\1*\2', string)
         tree = ast.parse(string, 'eval')
         expr = cls._fromast(tree)
         string = LinExpr._RE_NUM_VAR.sub(r'\1*\2', string)
         tree = ast.parse(string, 'eval')
         expr = cls._fromast(tree)


@@ -405,7 +407,7 @@ class LinExpr:
     @classmethod
     def fromsympy(cls, expr):
         """
     @classmethod
     def fromsympy(cls, expr):
         """

-        Create a linear expression from a sympy expression. Raise TypeError is
+        Create a linear expression from a SymPy expression. Raise TypeError is

         the sympy expression is not linear.
         """
         import sympy
         the sympy expression is not linear.
         """
         import sympy


@@ -416,7 +418,8 @@ class LinExpr:
             if symbol == sympy.S.One:
                 constant = coefficient
             elif isinstance(symbol, sympy.Dummy):
             if symbol == sympy.S.One:
                 constant = coefficient
             elif isinstance(symbol, sympy.Dummy):

-                # we cannot properly convert dummy symbols
+                # We cannot properly convert dummy symbols with respect to
+                # symbol equalities.

                 raise TypeError('cannot convert dummy symbols')
             elif isinstance(symbol, sympy.Symbol):
                 symbol = Symbol(symbol.name)
                 raise TypeError('cannot convert dummy symbols')
             elif isinstance(symbol, sympy.Symbol):
                 symbol = Symbol(symbol.name)


@@ -430,7 +433,7 @@ class LinExpr:
 
     def tosympy(self):
         """
 
     def tosympy(self):
         """

-        Convert the linear expression to a sympy expression.
+        Convert the linear expression to a SymPy expression.

         """
         import sympy
         expr = 0
         """
         import sympy
         expr = 0


@@ -477,6 +480,8 @@ class Symbol(LinExpr):
 
     @property
     def _coefficients(self):
 
     @property
     def _coefficients(self):

+        # This is not implemented as an attribute, because __hash__ is not
+        # callable in __new__ in class Dummy.

         return {self: Fraction(1)}
 
     @property
         return {self: Fraction(1)}
 
     @property