LpVariable

A class representing a linear variable

Attributes

low_bound: Union[int, float] property writable

Getter for lower bound of variable

name: str property readonly

Getter for name of variable

obj_coeff property readonly

Getter for the coefficient of the variable in the objective function

up_bound: Union[int, float] property writable

Getter for upper bound of variable

value: Union[int, float] property readonly

Getter for the value of the variable

var_type: VarType property writable

Getter for type of variable

Methods

evaluate(self)

Returns the value of the variable if set

Source code in flipy/lp_variable.py

def evaluate(self) -> Numeric:
    """ Returns the value of the variable if set """
    if self._value is None:
        raise ValueError('Value of variable %s is None' % self.name)
    return self._value

is_constant(self)

Tells whether the variable is restricted to a constant value

Source code in flipy/lp_variable.py

def is_constant(self) -> bool:
    """ Tells whether the variable is restricted to a constant value """
    return self.low_bound is not None and self.up_bound == self.low_bound

is_free(self)

Tells whether the variable is unbounded

Source code in flipy/lp_variable.py

def is_free(self) -> bool:
    """ Tells whether the variable is unbounded """
    return self.low_bound is None and self.up_bound is None

is_positive_free(self)

Tells whether the variable is an unbounded non-negative

Source code in flipy/lp_variable.py

def is_positive_free(self) -> bool:
    """ Tells whether the variable is an unbounded non-negative """
    return self.low_bound == 0 and self.up_bound is None

set_obj_coeff(self, coeff)

Setter for the objective coefficient of this variable

Parameters:

Name	Type	Description	Default
coeff	Union[int, float]	The coefficient of the variable in the objective function	required

Source code in flipy/lp_variable.py

def set_obj_coeff(self, coeff: Numeric):
    """ Setter for the objective coefficient of this variable

    Parameters
    ----------
    coeff
        The coefficient of the variable in the objective function
    """
    self._obj_coeff = coeff

set_value(self, value)

Setter for the value of the variable. Raises errors if not in bounds or if mismatched type.

Parameters:

Name	Type	Description	Default
value	Union[int, float]	The value to set for the variable	required

Exceptions:

Type	Description
ValueError	If value does not meet variable's bounds or variable type

Source code in flipy/lp_variable.py

def set_value(self, value: Numeric) -> None:
    """ Setter for the value of the variable. Raises errors if not in bounds or if mismatched type.

    Raises
    ------
    ValueError
        If value does not meet variable's bounds or variable type

    Parameters
    ----------
    value:
        The value to set for the variable
    """
    self._value = value

to_lp_str(self)

Converts variable into lp format

Source code in flipy/lp_variable.py

def to_lp_str(self) -> str:
    """ Converts variable into lp format """
    if self.is_free():
        return f'{self.name} free'
    if self.is_constant():
        return f'{self.name} = {self.low_bound:.12g}'

    if self.low_bound is None:
        lhs = '-inf <= '
    elif self.low_bound == 0 and self.var_type == VarType.Continuous:
        lhs = ''
    else:
        lhs = f'{self.low_bound:.12g} <= '

    if self.up_bound is not None:
        rhs = f' <= {self.up_bound:.12g}'
    else:
        rhs = ''
    return lhs + self.name + rhs