pyRCV2

pyRCV2 is an application for counting various preferential voting elections.

pyRCV2 may be used in a number of different ways:

• as an online web application, no installation or special software required, at https://yingtongli.me/rcv/
• as a standalone Python command line application
• as a library within another Python application

Features

pyRCV2 accepts data in the BLT file format, and can count votes using:

• weighted inclusive Gregory STV (e.g. Scottish STV)
• unweighted inclusive Gregory STV (e.g. Australian Senate STV)
• exclusive Gregory STV (e.g. PRSA 1977 and ERS97)
• Meek STV – with tree-packed ballots for efficient computation
• Wright STV

pyRCV2 is highly customisable, including options for:

• different quotas and quota rules (e.g. exact Droop, Hare) or progressively reducing quota
• calculations using fixed-point arithmetic, guarded fixed-point (quasi-exact) or exact rational numbers
• different tie breaking rules (backwards, random, manual) with auditable deterministic random number generation
• multiple constraints (e.g. affirmative action rules)
• extensible API for other counting methods

Online usage

After preparing the BLT file, head to https://yingtongli.me/rcv/. Select the BLT file, and click Count. pyRCV2 will count the election and display the results in a count sheet. See here for more detailed instructions.

By clicking Show advanced options, you can customise the options used for the count. A detailed explanation of the various options can be found here.

Once the count is complete, you can click Print result to generate a printable result report.

Command line usage

pyRCV2 may also be invoked as a command line application. Run python -m pyRCV2 --help to view help.

For example, run python -m pyRCV2 stv path/to/blt_file.blt --ties backwards --ties random --random-seed foobar.