qiskit.optimization.problems.LinearExpression

class LinearExpression(quadratic_program, coefficients)

Representation of a linear expression by its coefficients.

Creates a new linear expression.

The linear expression can be defined via an array, a list, a sparse matrix, or a dictionary that uses variable names or indices as keys and stores the values internally as a dok_matrix.

Parameters

• quadratic_program (Any) – The parent QuadraticProgram.

• coefficients (Union[ndarray, spmatrix, List[float], Dict[Union[int, str], float]]) – The (sparse) representation of the coefficients.

__init__(quadratic_program, coefficients)

Creates a new linear expression.

The linear expression can be defined via an array, a list, a sparse matrix, or a dictionary that uses variable names or indices as keys and stores the values internally as a dok_matrix.

Parameters

• quadratic_program (Any) – The parent QuadraticProgram.

• coefficients (Union[ndarray, spmatrix, List[float], Dict[Union[int, str], float]]) – The (sparse) representation of the coefficients.

Methods

__init__(quadratic_program, coefficients)	Creates a new linear expression.
evaluate(x)	Evaluate the linear expression for given variables.
evaluate_gradient(x)	Evaluate the gradient of the linear expression for given variables.
to_array()	Returns the coefficients of the linear expression as array.
to_dict([use_name])	Returns the coefficients of the linear expression as dictionary, either using variable names or indices as keys.

Attributes

coefficients	Returns the coefficients of the linear expression.
quadratic_program	Returns the parent QuadraticProgram.

property coefficients

Returns the coefficients of the linear expression.

Return type

dok_matrix

Returns

The coefficients of the linear expression.

evaluate(x)

Evaluate the linear expression for given variables.

Parameters

x (Union[ndarray, List, Dict[Union[int, str], float]]) – The values of the variables to be evaluated.

Return type

float

Returns

The value of the linear expression given the variable values.

evaluate_gradient(x)

Evaluate the gradient of the linear expression for given variables.

Parameters

x (Union[ndarray, List, Dict[Union[int, str], float]]) – The values of the variables to be evaluated.

Return type

ndarray

Returns

The value of the gradient of the linear expression given the variable values.

property quadratic_program

Returns the parent QuadraticProgram.

Return type

Any

Returns

The parent QuadraticProgram.

to_array()

Returns the coefficients of the linear expression as array.

Return type

ndarray

Returns

An array with the coefficients corresponding to the linear expression.

to_dict(use_name=False)

Returns the coefficients of the linear expression as dictionary, either using variable names or indices as keys.

Parameters

use_name (bool) – Determines whether to use index or names to refer to variables.

Return type

Dict[Union[int, str], float]

Returns

An dictionary with the coefficients corresponding to the linear expression.