Election Docs
Fall 2025
API

# District

o1.election.District
class District(val `name`: String, val `seats`: Int, val `candidates`: Vector[Candidate])

The class `District` represents electoral districts (Finnish: vaalipiiri). Each district has a certain number of seats for which a (larger) number of candidates compete in an election. Each district has its own candidates.

District objects are immutable.

## Parameters

candidates

  the candidates vying for the seats in the district

name

  the name of the electoral district

seats

  the number of seats (elected positions) available

## Attributes

Graph
Supertypes
  class Object
  trait Matchable
  class Any

## Members list

### Value members

#### Concrete methods

def candidatesByParty: Map[String, Vector[Candidate]]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns a mapping from parties to their candidates. That is, returns a `Map` whose keys are the names of all the parties that have candidates in this district. For each key, the value is a vector containing the candidates from that party in arbitrary order. (The order is arbitrary in the sense that the method is free to choose whichever order; this does not imply randomization.)

## Attributes

See also

  rankingsWithinParties

def candidatesFrom(`party`: String): Vector[Candidate]

Returns all the candidates in this district that belong to the party named by the parameter.

Returns all the candidates in this district that belong to the party named by the parameter.

## Attributes

def distributionFigures: Map[Candidate, Double]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns a mapping of candidates to their distribution figures (Finnish: vertailuluku). That is, returns a `Map` whose keys are all the candidates in this district and whose values are the distribution figures of those candidates.

The distribution figure of a candidate is obtained as follows. Take the position (rank) of the candidate in the ranking list within his or her own party (as defined by `rankingsWithinParties`). For instance, the most-voted-for candidate within a party has a rank of 1, the second-most-voted-for has a rank of two, and so on. Divide the total number of votes received by the candidate’s party by the candidate’s rank, and you have the candidate’s distribution figure.

If multiple candidates from a single party received the same number of votes, the arbitrary order chosen by `rankingsWithinParties` is used here, even though that would be an undesirable feature in a real-world system.

## Attributes

See also

  votesByParty

  rankingsWithinParties

  electedCandidates

def electedCandidates: Vector[Candidate]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns all the candidates who will be elected. The candidates with the highest distribution figures get elected; the total number of elected candidates equals seats.

If multiple candidates happen to have the same distribution figure, an arbitrary order is used, even though this would be an undesirable feature in a real-world system. (The order is arbitrary in the sense that the method is free to choose whichever order; this does not imply randomization.)

## Attributes

Returns

  the elected candidates in descending order by distribution figure

See also

  distributionFigures

def printCandidates(): Unit

Prints (to the console) a description of each candidate in this district, each on a line of its own. A candidate’s description is obtained by calling its `toString` method.

Prints (to the console) a description of each candidate in this district, each on a line of its own. A candidate’s description is obtained by calling its `toString` method.

NOTE TO STUDENTS: It’s not usually a good idea to create “print some of your data” methods (“return some information” methods are better), but we’re still making one as an exercise here. More about this in later chapters.

## Attributes

def rankingOfParties: Vector[String]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns a vector containing the names of all the parties that have candidates in this district, ordered by the total number of votes received by each party. Descending order is used, so the party with the most votes comes first.

If multiple parties received the same number of votes, this method orders them in an arbitrary way. (The order is arbitrary in the sense that the method is free to choose whichever order; this does not imply randomization.)

## Attributes

def rankingsWithinParties: Map[String, Vector[Candidate]]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns a mapping from parties to ranking lists of those parties’ candidates. That is, returns a `Map` whose keys are the names of all the parties that have candidates in this district. For each key, the value is a vector containing the candidates from that party in order by the number of votes they received, starting with the highest.

If multiple candidates from a single party received the same number of votes, this method returns those candidates in an arbitrary order. (Arbitrary in the sense that those candidates may be in whichever order, not in the sense of randomizing the order.)

## Attributes

override def toString: String

Returns a textual description of the district. The description is of the form `Name: X candidates, Y seats`, where `Name` is the name of the district, and `X` and `Y` the numbers of candidates and seats, respectively. For instance, might return the string `Helsinki: 1064 candidates, 85 seats`

Returns a textual description of the district. The description is of the form `Name: X candidates, Y seats`, where `Name` is the name of the district, and `X` and `Y` the numbers of candidates and seats, respectively. For instance, might return the string `Helsinki: 1064 candidates, 85 seats`

## Attributes

Definition Classes
  Any

def topCandidate: Option[Candidate]

Returns the top candidate (Finnish: ääniharava) of the district. That is, returns the candidate with the highest number of votes. If multiple candidates have the same number of votes, this method chooses one of them arbitrarily. (The choice is arbitrary in the sense that the method is free to choose whichever of the tied candidates; this does not imply randomization.)

Returns the top candidate (Finnish: ääniharava) of the district. That is, returns the candidate with the highest number of votes. If multiple candidates have the same number of votes, this method chooses one of them arbitrarily. (The choice is arbitrary in the sense that the method is free to choose whichever of the tied candidates; this does not imply randomization.)

## Attributes

Returns

  the top candidate, wrapped in an `Option`; `None` if there are no candidates at all

def topCandidatesByParty: Map[String, Candidate]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns a mapping from parties to their top candidates. That is, returns a `Map` whose keys are the names of all the parties that have candidates in this district. For each key, the value is the candidate from that party with the most votes.

If multiple candidates from one party received the same number of votes, this method chooses one of them arbitrarily. (The choice is arbitrary in the sense that the method is free to choose whichever of the tied candidates; this does not imply randomization.) The method assumes that every party has at least one candidate.

## Attributes

def totalVotes: Int

Returns the total number of votes received by all the candidates, that is, the total number of votes cast in this district.

Returns the total number of votes received by all the candidates, that is, the total number of votes cast in this district.

## Attributes

def totalVotes(`party`: String): Int

Returns the total number of votes received by members of the party named by the parameter.

Returns the total number of votes received by members of the party named by the parameter.

## Attributes

def votesByParty: Map[String, Int]

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

NOTE TO STUDENTS: THIS METHOD IS INTENDED FOR IMPLEMENTATION ONLY IN CHAPTER 10.1!

Returns a mapping from parties to their vote totals. That is, returns a `Map` whose keys are the names of all the parties that have candidates in this district. For each key, the value is the number of votes received in total by all the members of that party in this district.

## Attributes

#### Concrete fields

val candidates: Vector[Candidate]
val name: String
val seats: Int