LSExpression Class¶

class localsolver.LSExpression¶

Mathematical modeling expression. Expressions are used to build the mathematical optimization model associated to LocalSolver. An expression is composed of an operator (which corresponds to its type) and its operands (which are other expressions of the model).

See: LSModel
See: LSOperator

Summary¶

Methods¶
`GetModel`	Returns the model object associated to this expression.
`GetLocalSolver`	Returns the LocalSolver object associated to this expression.
`GetOperator`	Gets the operator of this expression.
`GetIndex`	Gets the index of this expression in the model.
`IsConstant`	Returns true if this expression is typed as constant in the model, false otherwise.
`IsDecision`	Returns true if this expression is typed as decision in the model, false otherwise.
`IsConstraint`	Returns true if this expression is tagged as constraint in the model, false otherwise.
`IsObjective`	Returns true if this expression is tagged as objective in the model, false otherwise.
`IsDouble`	Returns true if this expression is a double, false otherwise.
`IsInt`	Returns true if this expression is an integer, false otherwise.
`IsBool`	Returns true if this expression is a boolean (ie 0 or 1), false otherwise.
`IsArray`	Returns true if this expression is an array, false otherwise.
`IsCollection`	Returns true if this expression is a collection (list or set), false otherwise.
`IsFunction`	Returns true if this expression is a function, false otherwise.
`AddOperand`	Adds the given operand to this expression.
`AddOperands`	Add the given operands to the expression.
`GetOperand`	Gets the operand with the given index.
`SetOperand`	Replaces the operand of the given index.
`GetNbOperands`	Gets the number of operands of this expression.
`SetValue`	Sets the value of this expression in the current solution found by the solver.
`SetIntValue`	Sets the value of this expression in the current solution found by the solver.
`SetDoubleValue`	Sets the value of this expression in the current solution found by the solver.
`GetValue`	Gets the value of this expression in the best solution found by the solver.
`GetIntValue`	Gets the value of this expression in the best solution found by the solver.
`GetDoubleValue`	Gets the value of this expression in the best solution found by the solver.
`GetCollectionValue`	Gets the value of this expression in the best solution found by the solver.
`GetArrayValue`	Gets the value of this expression in the best solution found by the solver.
`GetExternalContext`	Gets the external function context of this expression.
`IsViolated`	Returns true if the given expression is violated in the best solution found by the solver.
`IsUndefined`	Returns true if the given expression has an undefined value in the best solution found by the solver.
`SetName`	Sets the name of this expression.
`IsNamed`	Returns true if this expression has a name, and false otherwise.
`GetName`	Gets the name of this expression or the empty string if no name has been set.
`ToString`	Returns a string representation of this expression.

Overloaded operators¶
`operator +`	Creates a new LSOperator.Sum expression.
`operator -`	Creates a new LSOperator.Sub expression.
`operator *`	Creates a new LSOperator.Prod expression.
`operator /`	Creates a new LSOperator.Div expression.
`operator %`	Creates a new LSOperator.Mod expression.
`operator !`	Creates a new LSOperator.Not expression.
`operator &`	Creates a new LSOperator.And expression.
`operator \|`	Creates a new LSOperator.Or expression.
`operator ^`	Creates a new LSOperator.Xor expression.
`operator ==`	Creates a new LSOperator.Eq expression.
`operator !=`	Creates a new LSOperator.Neq expression.
`operator >=`	Creates a new LSOperator.Geq expression.
`operator <=`	Creates a new LSOperator.Leq expression.
`operator >`	Creates a new LSOperator.Gt expression.
`operator <`	Creates a new LSOperator.Lt expression.
`this`	Creates a new LSOperator.At expression.

Instance methods¶

LSModel GetModel()¶

Returns the model object associated to this expression.

Returns: LSModel object
Return type: LSModel

LocalSolver GetLocalSolver()¶

Returns the LocalSolver object associated to this expression.

Returns: LocalSolver object
Return type: LocalSolver

LSOperator GetOperator()¶

Gets the operator of this expression.

Returns: Operator.
Return type: LSOperator

int GetIndex()¶

Gets the index of this expression in the model.

Returns: Index in the model.
Return type: int

bool IsConstant()¶

Returns true if this expression is typed as constant in the model, false otherwise.

Returns: True if typed as constant.
Return type: bool

bool IsDecision()¶

Returns true if this expression is typed as decision in the model, false otherwise.

Returns: True if typed as decision.
Return type: bool

bool IsConstraint()¶

Returns true if this expression is tagged as constraint in the model, false otherwise.

Returns: True if tagged as constraint.
Return type: bool

bool IsObjective()¶

Returns true if this expression is tagged as objective in the model, false otherwise.

Returns: True if tagged as objective.
Return type: bool

bool IsDouble()¶

Returns true if this expression is a double, false otherwise. Only allowed in states Paused or Stopped.

Since: 3.0
Returns: True if the expression is a double.
Return type: bool

bool IsInt()¶

Returns true if this expression is an integer, false otherwise. Only allowed in states Paused or Stopped. Note that a boolean is also an integer.

Since: 3.0
Returns: True if the expression is an integer.
Return type: bool

bool IsBool()¶

Returns true if this expression is a boolean (ie 0 or 1), false otherwise. Only allowed in states Paused or Stopped.

Since: 3.0
Returns: True if the expression is a boolean.
Return type: bool

bool IsArray()¶

Returns true if this expression is an array, false otherwise. Only allowed in states Paused or Stopped.

Since: 3.1
Returns: True if the expression is an array.
Return type: bool

bool IsCollection()¶

Returns true if this expression is a collection (list or set), false otherwise. Only allowed in states Paused or Stopped.

Since: 5.5
Returns: True if the expression is a collection.
Return type: bool

bool IsFunction()¶

Returns true if this expression is a function, false otherwise. Only allowed in states Paused or Stopped.

Since: 6.0
Returns: True if the expression is a function.

void AddOperand(LSExpression expr)¶

void AddOperand(long constant)

void AddOperand(double constant)

Adds the given operand to this expression. Only allowed in state Modeling.

Arguments: expr – Operand to add.

void AddOperands(IEnumerable<LSExpression> operands)¶

void AddOperands(IEnumerable<long> operands)

void AddOperands(IEnumerable<double> operands)

void AddOperands(params LSExpression[] operands)

void AddOperands(params long[] operands)

void AddOperands(params double[] operands)

Add the given operands to the expression.

Arguments: operands – The operands to be added.

LSExpression GetOperand(int operandIndex)¶

Gets the operand with the given index.

Arguments: operandIndex – Index of the operand.
Returns: Operand.
Return type: LSExpression

void SetOperand(int operandIndex, LSExpression operand)¶

void SetOperand(int operandIndex, long constant)

void SetOperand(int operandIndex, double constant)

Replaces the operand of the given index.

Arguments

operandIndex (int) – Index of the operand to change
operand – New operand

int GetNbOperands()¶

Gets the number of operands of this expression.

Returns: Number of operands.
Return type: int

void SetValue(long value)¶

Sets the value of this expression in the current solution found by the solver. Only allowed for decisions. Only allowed in state Stopped. Only allowed if this expression is an integer or a boolean. If the solver was not launched, this value will be used as an initial value for the decision.

This method is a shortcut for LSSolution.SetIntValue(LSExpression, long) and has the same behavior as LSExpression.SetIntValue(long).

Arguments: value (long) – Value assigned to this expression.
See: LSSolution.SetIntValue(LSExpression, long)
See: LSExpression.IsInt
See: LSExpression.IsBool

void SetValue(double value)

Sets the value of this expression in the current solution found by the solver. Only allowed for decisions. Only allowed in state :field`~LSState.Stopped`. Only allowed if this expression is an integer or a boolean. If the solver was not launched, this value will be used as an initial value for the decision.

This method is a shortcut for LSSolution.SetDoubleValue(LSExpression, double) and has the same behavior as LSExpression.SetDoubleValue(double).

Arguments: value (double) – Value assigned to this expression.
See: LSSolution.SetDoubleValue(LSExpression, double)
See: LSExpression.IsDouble

void SetIntValue(long value)¶

Sets the value of this expression in the current solution found by the solver. Only allowed for decisions. Only allowed in state Stopped. Only allowed if this expression is an integer or a boolean. If the solver was not launched, this value will be used as an initial value for the decision.

This method is a shortcut for LSSolution.SetIntValue(LSExpression, long).

Since: 3.0
Arguments: value (long) – Value assigned to this expression.
See: LSSolution.SetIntValue
See: LSExpression.IsInt
See: LSExpression.IsBool

void SetDoubleValue(double value)¶

Sets the value of this expression in the current solution found by the solver.

Only allowed for decisions. Only allowed in state Stopped. Only allowed if this expression is a double. If the solver was not launched, this value will be used as an initial value for the decision.

This method is a shortcut for LSSolution.SetDoubleValue(LSExpression, double).

Since: 3.0
Arguments: value (double) – Value assigned to this expression.
See: LSSolution.SetDoubleValue
See: LSExpression.IsDouble

long GetValue()¶

Gets the value of this expression in the best solution found by the solver. Only allowed in states Paused or Stopped. Only allowed if this expression is an integer or a boolean.

This method is a shortcut for LSSolution.GetIntValue(LSExpression) and has the same behavior as LSExpression.GetIntValue(LSExpression).

Returns: Value in the best solution.
Return type: long
See: LSSolution.GetValue
See: LSExpression.IsInt
See: LSExpression.IsBool

long GetIntValue()¶

Gets the value of this expression in the best solution found by the solver. Only allowed in states Paused or Stopped. Only allowed if this expression is an integer or a boolean.

This method is a shortcut for LSSolution.GetIntValue(LSExpression).

Since: 3.0
Returns: Value in the best solution.
Return type: long
See: LSSolution.GetIntValue
See: LSExpression.IsInt
See: LSExpression.IsBool

double GetDoubleValue()¶

Gets the value of this expression in the best solution found by the solver. Only allowed in states Paused or Stopped. Only allowed if this expression is a double.

This method is a shortcut for LSSolution.GetDoubleValue(LSExpression).

Since: 3.0
Returns: Value in the best solution.
Return type: double
See: LSSolution.GetDoubleValue
See: LSExpression.IsDouble

LSCollection GetCollectionValue()¶

Gets the value of this expression in the best solution found by the solver. Only allowed in states Paused or Stopped. Only allowed if this expression is a collection (list).

This method is a shortcut for LSSolution.GetCollectionValue(LSExpression).

Since: 5.5
Returns: Value in the best solution.
Return type: LSCollection
See: LSSolution.GetCollectionValue
See: LSExpression.IsCollection

LSArray GetArrayValue()¶

Gets the value of this expression in the best solution found by the solver. Only allowed in states Paused or Stopped. Only allowed if this expression is an array.

This method is a shortcut for LSSolution.GetArrayValue(LSExpression).

Since: 7.5
Returns: Value in the best solution.
Return type: LSArray
See: LSSolution.GetCollectionValue
See: LSExpression.IsArray

LSExternalContext GetExternalContext()¶

Gets the external function context of this expression. Only allowed if this expression is an external function.

Since: 9.5
Returns: Context of the external function
Return type: LSExternalContext

bool IsViolated()¶

Returns true if the given expression is violated in the best solution found by the solver. An expression can be violated in 3 cases:

It is a constraint and its value is 0.
It is a a double and its value is NaN (Not A Number).
It is an integer or boolean with no valid value (arithmetic or out of bounds exception).

Only allowed in states Paused or Stopped. This method is a shortcut for LSSolution.IsViolated(LSExpression).

Since: 5.5
Returns: True if this expression is violated in the best solution.
Return type: bool

bool IsUndefined()¶

Returns true if the given expression has an undefined value in the best solution found by the solver. An expression can be undefined in 2 cases:

It is a a double and its value is NaN (NotANumber).
It is an integer or boolean with no valid value (arithmetic or out of bounds exception).

Only allowed in states Paused or Stopped. This method is a shortcut for LSSolution.IsUndefined(LSExpression).

Since: 7.0
Returns: True if this expression has an undefined value in the best solution.
Return type: bool

void SetName(string name)¶

Sets the name of this expression. Only allowed in state Modeling. The name cannot be empty. Two operators of the model cannot share the same name. Useful for debugging or logging purposes.

Arguments: name (string) – Name.

bool IsNamed()¶

Returns true if this expression has a name, and false otherwise.

Returns: True if named.
Return type: bool

string GetName()¶

Gets the name of this expression or the empty string if no name has been set.

Returns: Name.
Return type: string

string ToString()¶

Returns a string representation of this expression. This representation provides the index of the expression, its type, and its name (if any). Useful for debugging or logging purposes.

Returns: String representation.
Return type: string

Overloaded operators and indexers¶

LSExpression operator +(LSExpression expr1, LSExpression expr2)¶

LSExpression operator +(LSExpression expr1, long expr2)

LSExpression operator +(LSExpression expr1, double expr2)

LSExpression operator +(long expr1, LSExpression expr2)

LSExpression operator +(double expr1, LSExpression expr2)

Creates a new LSOperator.Sum expression. It is a shortcut for model.CreateExpression(LSOperator.Sum, expr1, expr2).

Arguments

expr1 – First operand. Can be an LSExpression, an integer or a double.
expr2 – Second operand. Can be an LSExpression, an integer or a double.

Returns

A new LSOperator.Sum expression

Return type

LSExpression

LSExpression operator -(LSExpression expr1, LSExpression expr2)¶

LSExpression operator -(LSExpression expr1, long expr2)

LSExpression operator -(LSExpression expr1, double expr2)

LSExpression operator -(long expr1, LSExpression expr2)

LSExpression operator -(double expr1, LSExpression expr2)

Creates a new LSOperator.Sub expression. It is a shortcut for model.CreateExpression(LSOperator.Sub, expr1, expr2).

Arguments

expr1 – First operand. Can be an LSExpression, an integer or a double.
expr2 – Second operand. Can be an LSExpression, an integer or a double.

Returns

A new LSOperator.Sub expression

Return type

LSExpression

LSExpression operator *(LSExpression expr1, LSExpression expr2)¶

LSExpression operator *(LSExpression expr1, long expr2)

LSExpression operator *(LSExpression expr1, double expr2)

LSExpression operator *(long expr1, LSExpression expr2)

LSExpression operator *(double expr1, LSExpression expr2)

Creates a new LSOperator.Prod expression. It is a shortcut for model.CreateExpression(LSOperator.Prod, expr1, expr2).

Arguments

expr1 – First operand. Can be an LSExpression, an integer or a double.
expr2 – Second operand. Can be an LSExpression, an integer or a double.

Returns

A new LSOperator.Prod expression

Return type

LSExpression

LSExpression operator /(LSExpression expr1, LSExpression expr2)¶

LSExpression operator /(LSExpression expr1, long expr2)

LSExpression operator /(LSExpression expr1, double expr2)

LSExpression operator /(long expr1, LSExpression expr2)

LSExpression operator /(double expr1, LSExpression expr2)

Creates a new LSOperator.Div expression. It is a shortcut for model.CreateExpression(LSOperator.Div, expr1, expr2).

Arguments

expr1 – First operand. Can be an LSExpression, an integer or a double.
expr2 – Second operand. Can be an LSExpression, an integer or a double.

Returns

A new LSOperator.Div expression

Return type

LSExpression

LSExpression operator %(LSExpression expr1, LSExpression expr2)¶

LSExpression operator %(LSExpression expr1, long expr2)

LSExpression operator %(long expr1, LSExpression expr2)

Creates a new LSOperator.Mod expression. It is a shortcut for model.CreateExpression(LSOperator.Mod, expr1, expr2).

Arguments

expr1 – First operand. Can be an LSExpression or an integer.
expr2 – Second operand. Can be an LSExpression or an integer.

Returns

A new LSOperator.Mod expression

Return type

LSExpression

LSExpression operator !(LSExpression expr)¶

Creates a new LSOperator.Not expression. It is a shortcut for model.create_expression(LSOperator.Not, expr).

Returns: A new LSOperator.Not expression
Return type: LSExpression

LSExpression operator &(LSExpression expr1, LSExpression expr2)¶

Creates a new LSOperator.And expression. It is a shortcut for model.CreateExpression(LSOperator.And, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.And expression

Return type

LSExpression

LSExpression operator |(LSExpression expr1, LSExpression expr2)¶

Creates a new LSOperator.Or expression. It is a shortcut for model.CreateExpression(LSOperator.Or, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Or expression

Return type

LSExpression

LSExpression operator ^(LSExpression expr1, LSExpression expr2)¶

Creates a new LSOperator.Xor expression. It is a shortcut for model.CreateExpression(LSOperator.Xor, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.And expression

Return type

LSExpression

LSExpression operator ==(LSExpression expr1, LSExpression expr2)¶

LSExpression operator ==(LSExpression expr1, long expr2)

LSExpression operator ==(LSExpression expr1, double expr2)

LSExpression operator ==(long expr1, LSExpression expr2)

LSExpression operator ==(double expr1, LSExpression expr2)

Creates a new LSOperator.Eq expression. It is a shortcut for model.CreateExpression(LSOperator.Eq, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Eq expression

Return type

LSExpression

LSExpression operator !=(LSExpression expr1, LSExpression expr2)¶

LSExpression operator !=(LSExpression expr1, long expr2)

LSExpression operator !=(LSExpression expr1, double expr2)

LSExpression operator !=(long expr1, LSExpression expr2)

LSExpression operator !=(double expr1, LSExpression expr2)

Creates a new LSOperator.Neq expression. It is a shortcut for model.CreateExpression(LSOperator.Neq, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Neq expression

Return type

LSExpression

LSExpression operator >=(LSExpression expr1, LSExpression expr2)¶

LSExpression operator >=(LSExpression expr1, long expr2)

LSExpression operator >=(LSExpression expr1, double expr2)

LSExpression operator >=(long expr1, LSExpression expr2)

LSExpression operator >=(double expr1, LSExpression expr2)

Creates a new LSOperator.Geq expression. It is a shortcut for model.CreateExpression(LSOperator.Geq, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Geq expression

Return type

LSExpression

LSExpression operator <=(LSExpression expr1, LSExpression expr2)¶

LSExpression operator <=(LSExpression expr1, long expr2)

LSExpression operator <=(LSExpression expr1, double expr2)

LSExpression operator <=(long expr1, LSExpression expr2)

LSExpression operator <=(double expr1, LSExpression expr2)

Creates a new LSOperator.Leq expression. It is a shortcut for model.CreateExpression(LSOperator.Leq, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Neq expression

Return type

LSExpression

LSExpression operator >(LSExpression expr1, LSExpression expr2)¶

LSExpression operator >(LSExpression expr1, long expr2)

LSExpression operator >(LSExpression expr1, double expr2)

LSExpression operator >(long expr1, LSExpression expr2)

LSExpression operator >(double expr1, LSExpression expr2)

Creates a new LSOperator.Gt expression. It is a shortcut for model.CreateExpression(LSOperator.Gt, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Gt expression

Return type

LSExpression

LSExpression operator <(LSExpression expr1, LSExpression expr2)¶

LSExpression operator <(LSExpression expr1, long expr2)

LSExpression operator <(LSExpression expr1, double expr2)

LSExpression operator <(long expr1, LSExpression expr2)

LSExpression operator <(double expr1, LSExpression expr2)

Creates a new LSOperator.Lt expression. It is a shortcut for model.CreateExpression(LSOperator.Lt, expr1, expr2).

Arguments

expr1 (LSExpression) – First operand.
expr2 (LSExpression) – Second operand.

Returns

A new LSOperator.Lt expression

Return type

LSExpression

LSExpression this(long index)¶

LSExpression this(LSExpression index)

LSExpression this(LSExpression index1, LSExpression index2)

LSExpression this(LSExpression index1, long index2)

LSExpression this(long index1, LSExpression index2)

LSExpression this(long index1, long index2)

Creates a new LSOperator.At expression. It is a shortcut for model.CreateExpression(LSOperator.At, index, ...).

Returns: A new LSOperator.At expression
Return type: LSExpression