Matrix¶

class whalrus.Matrix(*args, converter: whalrus.converters_ballot.converter_ballot.ConverterBallot = None, **kwargs)[source]¶

A way to compute a matrix from a profile.

A Matrix object is a callable whose inputs are ballots and optionally weights, voters and candidates. When it is called, it loads the profile. The output of the call is the Matrix object itself. But after the call, you can access to the computed variables (ending with an underscore), such as as_dict_ or as_array_.

Parameters

args – If present, these parameters will be passed to __call__ immediately after initialization.
converter (ConverterBallot) – The converter that is used to convert input ballots in order to compute profile_converted_. Default: ConverterBallotGeneral.
kwargs – If present, these parameters will be passed to __call__ immediately after initialization.

profile_original_¶

The profile as it is entered by the user. This uses the constructor of Profile. Hence indirectly, it uses ConverterBallotGeneral to ensure, for example, that strings like 'a > b > c' are converted to :class:Ballot objects.

Type: Profile

profile_converted_¶

The profile, with ballots that are adequate for the voting rule. For example, in MatrixWeightedMajority, it will be BallotOrder objects. This uses the parameter converter of the object.

Type: Profile

candidates_¶

The candidates of the election, as entered in the __call__.

Type: NiceSet

Examples

Cf. MatrixWeightedMajority for some examples.

property as_array_¶

The matrix, as a numpy array. Each row and each column corresponds to a candidate (in the order of candidates_as_list_).

Type: Array

property as_array_of_floats_¶

The matrix, as a numpy array. It is the same as as_array_, but converted to floats.

Type: Array

property as_dict_¶

The matrix, as a NiceDict. Keys are pairs of candidates, and values are the coefficients of the matrix.

Type: NiceDict

property candidates_as_list_¶

The list of candidates. Candidates are sorted if possible.

Type: list

property candidates_indexes_¶

The candidates as a dictionary. To each candidate, it associates its index in candidates_as_list_.

Type: NiceDict