Support for fractional votes

[JDziurlaj]

Support the expression of fractional votes, either as decimal fractions (e.g. 0.25) or as a rational number (e.g. 1/4)

Rationale

This change is suggested to improve support for voting methods that produce fractional values, e.g. RCV and Cumulative voting.

The attributes CVRContestSelection::TotalNumberVotes and SelectionPosition::NumberVotes are typed as Integer, which makes expressing fractional values impossible.

Approach

The approach is driven by the following constraints:

• Consumers must not have to look at additional fields to parse vote counts for plurality voting
• Consumers should be able to interpret whole votes as numbers without any additional parsing or casting when data binding

Thus, the existing attributes will remain unchanged. Instead this proposal adds two attributes, CVRContestSelection::TotalFractionalVotes and SelectionPosition::FractionalVotes as a String type. When represented as XML or JSON, a pattern constraint will be added, as the following regular expression:

([0-9]+/[1-9]+[0-9]*)|(\.[0-9]+)

• All digits are are assumed to represent a base-10 (i.e. decimal) value
• If a rational number is used, the numerator must be less than the denominator (cannot represent numbers >= 1 e.g. 2/1)

When a decimal numerals are used, they must begin with a decimal separator (e.g. a decimal point)

{
    "FractionalVotes": ".25" 
}

This is to make conversion easier, for example 1/4 will cast to 0.25 in a programming language such as Python or JavaScript.

{
    "FractionalVotes": "1/4" 
}

I am open to other names for the attributes, so long as they are clear and concise!

[HerbDeutsch]

Taking this from the email chain that had comments for documentation here: Herb Question: ¼ is an easy one since it is an exact decimal. What about 1/3 or other fraction that is a continuous decimal. It would have to terminate and not be exact.

John Response: Fractions expressed as numerator/denominator are allowed. The entire expression is expected to be placed into the NumberVotesFraction e.g. { “NumberVotes”: 1 “NumberVotesFraction”: “1/3” }

Herb: Response: OK. I’m good with that.