Struct tallystick::score::ScoreTally

pub struct ScoreTally<T, C = u64> where
    T: Eq + Clone + Hash,
    C: Copy + PartialOrd + AddAssign + Num + NumCast,  { /* fields omitted */ }

A generic score tally.

Generics:

• T: The candidate type.
• C: The count and score type. u64 is recommended, but can be modified to use a different type for counting votes (eg f64 for fractional scores).

Example

   use tallystick::score::ScoreTally;

   // An election for Judge using floats as the score type.
   let mut tally = ScoreTally::<&str, f64>::new(1);
   tally.add(vec![("Judge Judy", 3.5), ("Notorious RBG", 2.5)]);
   tally.add(vec![("Judge Dredd", 0.5)]);
   tally.add(vec![("Abe Vigoda", 6.1), ("Notorious RBG", 3.2)]);
   tally.add(vec![("Judge Dredd", 1.0), ("Notorious RBG", 4.1)]);

   let winners = tally.winners().into_unranked();
   assert!(winners[0] == "Notorious RBG");

Implementations

impl<T, C> ScoreTally<T, C> where
    T: Eq + Clone + Hash,
    C: Copy + PartialOrd + AddAssign + Num + NumCast, 

pub fn new(num_winners: usize) -> Self

Create a new ScoreTally with the given number of winners.

If there is a tie, the number of winners might be more than num_winners. (See winners() for more information on ties.)

pub fn with_capacity(num_winners: usize, expected_candidates: usize) -> Self

Create a new ScoreTally with the given number of winners, and number of expected candidates.

pub fn add(&mut self, selection: Vec<(T, C)>)

Add a new vote

pub fn add_ref(&mut self, selection: &[(T, C)])

Add a vote by reference.

pub fn add_weighted(&mut self, selection: Vec<(T, C)>, weight: C)

Add a weighted vote. By default takes a weight as a usize integer, but can be customized by using ApprovalTally with a custom vote type.

pub fn add_weighted_ref(&mut self, selection: &[(T, C)], weight: C)

Add a weighted vote by reference.

pub fn candidates(&self) -> Vec<T>

Get a list of all candidates seen by this tally. Candidates are returned in no particular order.

pub fn winners(&self) -> RankedWinners<T>

Get a ranked list of winners. Winners with the same rank are tied. The number of winners might be greater than the requested num_winners if there is a tie. In score voting, the winning candidate(s) is the one with the highest total score.

pub fn totals(&self) -> Vec<(T, C)>

Get vote totals for this tally.

Each candidate has a total thhat is equal to the sum of all scores for that candidate.

Example

   use tallystick::score::DefaultScoreTally;

   let mut tally = DefaultScoreTally::new(1);
   tally.add(vec![("Alice", 30), ("Bob", 10)]);
   tally.add(vec![("Bob", 10), ("Carol", 5)]);

   for (candidate, score) in tally.totals().iter() {
      println!("{} got a score of {}", candidate, score);
   }
   // Prints:
   //   Alice got a score of 30
   //   Bob got a score of 20
   //   Carol got a score of 5

pub fn ranked(&self) -> Vec<RankedCandidate<T>>

Get a ranked list of all candidates. Candidates with the same rank are tied. Candidates are ranked in ascending order. The highest ranked candidate has a rank of 0.

Example

   use tallystick::score::DefaultScoreTally;

   let mut tally = DefaultScoreTally::new(1);
   tally.add(vec![("Alice", 30), ("Bob", 10)]);
   tally.add(vec![("Bob", 10), ("Carol", 5)]);
    
   for ranked in tally.ranked().iter() {
      println!("{} has a rank of {}", ranked.candidate, ranked.rank);
   }
   // Prints:
   //   Alice has a rank of 0
   //   Bob has a rank of 1
   //   Carol has a rank of 2