# RandTauVectorGridUniform¶

class poisson_approval.RandTauVectorGridUniform(denominator, ballots=None, d_ballot_fixed_share=None, **kwargs)[source]

A random factory of tau-vectors (TauVector), uniform on a grid.

Parameters: denominator (int) – The grain of the grid. ballots (iterable, optional) – These ballots (e.g. 'a', 'ab') will have a variable share. Default: all allowed ballots. d_ballot_fixed_share (dict, optional) – A dictionary. For each entry ballot: fixed_share, this ballot will have at least this fixed share. The total must be lower or equal to 1. kwargs (keyword arguments) – These additional arguments will be passed directly to TauVector.

Examples

Basic usage:

>>> initialize_random_seeds()
>>> rand_tau = RandTauVectorGridUniform(denominator=7)
>>> tau = rand_tau()
>>> print(tau)
<a: 2/7, ab: 1/7, ac: 1/7, b: 3/7> ==> a, b


If the voting rule is not approval, only the relevant ballots are used:

>>> initialize_random_seeds()
>>> rand_tau = RandTauVectorGridUniform(denominator=7, voting_rule=PLURALITY)
>>> tau = rand_tau()
>>> print(tau)
<a: 2/7, b: 4/7, c: 1/7> ==> b (Plurality)


Using the optional parameters:

>>> from fractions import Fraction
>>> rand_tau = RandTauVectorGridUniform(
...     denominator=5,
...     ballots=['b', 'bc'], d_ballot_fixed_share={'a': Fraction(2, 7)},
...     symbolic=True)
>>> tau = rand_tau()
>>> print(tau)
<a: 2/7, b: 1/7, bc: 4/7> ==> b


For more examples, cf. RandSimplexGridUniform.