schulze_voting

The Schulze voting procedure is explained in more detail on Wikipedia. This pure python library can be used to evaluate such votings.

Installation

Just install via pip:

pip install schulze_voting

Creating a Schulze Voting

This library supports weighted votes, that is each person / group that casts a vote can have a weight > 0 (for example weighted according to a number of people the group represents). Suppose that there are 4 options to vote for (A, B, C and D). The voter wants to rank A > B = D > C. And the voter has a weight of 2. Then this vote can be created with the following code:

vote = SchulzeVote([0, 1, 2, 1], 2)

The lists simply assigns each option a rank (smaller rank means ranked higher). So here A has the highest rank, B and D both have the second highest rank and C has the lowest rank.

There a different methods to compute (intermediate) results from lists of such votes:

• compute_d
• compute_p
• rank_p
• evaluate_schulze: Computes the matrices d and p and ranks p.

The ranking of p is returned as a list of list of ints. The first list contains all options that are ranked highest, the next list all entries ranked second best and so on.

So if the result is that A = C > B = D > E the result would contain [[0, 2], [1, 3], [4]].

See the source code for more documentation and examples.

License

MIT License

Copyright (c) 2018 Fabian Wenzelmann

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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