QuadraticExpression
QuadraticExpression(quadratic_program, coefficients)
Representation of a quadratic expression by its coefficients.
Creates a new quadratic expression.
The quadratic 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. We stores values in a compressed way, i.e., values at symmetric positions are summed up in the upper triangle. For example, {(0, 1): 1, (1, 0): 2} -> {(0, 1): 3}.
Parameters
- quadratic_program (
Any
) – The parent QuadraticProgram. - coefficients (
Union
[ndarray
,spmatrix
,List
[List
[float
]],Dict
[Tuple
[Union
[int
,str
],Union
[int
,str
]],float
]]) – The (sparse) representation of the coefficients.
Attributes
coefficients
scipy.sparse.dok.dok_matrix
Returns the coefficients of the quadratic expression.
Return type
dok_matrix
Returns
The coefficients of the quadratic expression.
quadratic_program
Any
Returns the parent QuadraticProgram.
Return type
Any
Returns
The parent QuadraticProgram.
Methods
__getitem__
QuadraticExpression.__getitem__(key)
Returns the coefficient where i, j can be a variable names or indices.
Parameters
key (Tuple
[Union
[int
, str
], Union
[int
, str
]]) – The tuple of indices or names of the variables corresponding to the coefficient.
Return type
float
Returns
The coefficient corresponding to the addressed variables.
evaluate
QuadraticExpression.evaluate(x)
Evaluate the quadratic expression for given variables: x * Q * x.
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 quadratic expression given the variable values.
to_array
QuadraticExpression.to_array(symmetric=False)
Returns the coefficients of the quadratic expression as array.
Parameters
symmetric (bool
) – Determines whether the output is in a symmetric form or not.
Return type
ndarray
Returns
An array with the coefficients corresponding to the quadratic expression.
to_dict
QuadraticExpression.to_dict(symmetric=False, use_name=False)
Returns the coefficients of the quadratic expression as dictionary, either using tuples of variable names or indices as keys.
Parameters
- symmetric (
bool
) – Determines whether the output is in a symmetric form or not. - use_name (
bool
) – Determines whether to use index or names to refer to variables.
Return type
Dict
[Union
[Tuple
[int
, int
], Tuple
[str
, str
]], float
]
Returns
An dictionary with the coefficients corresponding to the quadratic expression.