PriorityUnambiguous

class whalrus.PriorityUnambiguous[source]

When there are two elements or more, raise a ValueError.

Examples

>>> try:
...     Priority.UNAMBIGUOUS.choice({'a', 'b'})
... except ValueError:
...     print('Cannot choose')
Cannot choose
>>> try:
...     Priority.UNAMBIGUOUS.sort({'a', 'b'})
... except ValueError:
...     print('Cannot sort')
Cannot sort
choice(x: Union[set, list], reverse: bool = False) → object

Choose an element from a list, set, etc.

Parameters

  • x (list, set, etc.) – The list, set, etc where the element is to be chosen.

  • reverse (bool) – If False (default), then we choose the “first” or “best” element in this priority order. For example, if this is the ascending priority, we choose the lowest element. If True, then we choose the “last” or “worst” element. This is used, for example, in RuleVeto.

Returns

The chosen element (or None). When x is empty, return None. When x has one element, return this element.

Return type

object

compare(c, d) → int[source]

Compare two candidates.

Parameters

  • c (candidate) –

  • d (candidate.) –

Returns

0 if c = d, -1 if the tie is broken in favor of c over d, 1 otherwise.

Return type

int

sort(x: Union[set, list], reverse: bool = False) → Optional[list]

Sort a list, set, etc.

The original list x is not modified.

Parameters

  • x (list, set, etc.) –

  • reverse (bool) – If True, we use the reverse priority order.

Returns

A sorted list (or None).

Return type

list or None

sort_pairs_rp(x: Union[set, list], reverse: bool = False) → Optional[list]

Sort a list, set, etc. of pairs of candidates (for Ranked Pairs).

By default, it is in the normal priority order for the first element of the pair, and in the reverse priority order for the second element of the pair.

The original list x is not modified.

Parameters

  • x (list, set, etc.) –

  • reverse (bool) – If True, we use the reverse priority order.

Returns

A sorted list (or None).

Return type

list or None