As in python Social Choice Function. The main export is the class
Profile, as in a voting profile. Then there are methods to get the best
candidate in a profile, or to get the score of an individual candidate.
A profile is a set of (number of votes, ballot) pairs where a ballot is
some ordering of the candidates. For example:
collectedVotes = Profile({(40,(0,1,2)),(28,(1,2,0)),(32,(2,1,0))})
That means 40 people like candidate 0 most, then candidate 1 middle, and hate candidate 2. 28 people like candidate 1 the most and so on.
If your set of candidates is S, then each the ballot should contain each
element in S exactly once, in any order. Your candidates can be any hashable
objects.
weirdProfile = Profile({(40,(2,1,56.78)),(28,(1,56.78,2)),(32,(56.78,1,2))})
>>> weirdProfile.mayors
set(56.78, 1, 'fish')
And of course you can run elections:
>>> weirdProfile.singleTransferableVote()
set([56.78])
$ pip3 install socho
from socho.profile import Profile, ballot_box, plurality ballots = [(2,1,56.78), (2,1,56.78), (2,1,56.78), (1,56.78,2), (1,56.78,2), (56.78,1,2), (56.78,1,2)] # Create a profile profile = Profile.ballot_box(ballots) scorer = profile.borda # function to calculate score for each mayor # A mayor list ranked by score # [(2, 10), (0, 7), (1, 4)] # maps to [(56.78, 10), (1, 7), (2, 4)] rank = profile.ranking(scorer) # 56.78 is the winner # 1 as 2nd place # 2 as 3rd place
usage: socho [-h] -i INPUT_FILEPATH [-p PREDICTIONS_FILEPATH] [-s SEP] -f
{borda,plurality,simpson,copeland,dowdall,symmetric_borda}
[-o OUTPUT_FILEPATH] [-c COMPARE_FILEPATH]
optional arguments:
-h, --help show this help message and exit
-i INPUT_FILEPATH, --input INPUT_FILEPATH
Path to input file.
-p PREDICTIONS_FILEPATH, --predictions PREDICTIONS_FILEPATH
Path to predictions file (required for plurality).
-s SEP, --sep SEP File separator, i. e., ',' or ' '...
-f {borda,plurality,simpson,copeland,dowdall,symmetric_borda}, --function {borda,plurality,simpson,copeland,dowdall,symmetric_borda}
Social choice function.
-o OUTPUT_FILEPATH, --output OUTPUT_FILEPATH
Path to output file.
-c COMPARE_FILEPATH, --compare COMPARE_FILEPATH
Path to rank file to be compared.$ socho -i tests/input.txt -f borda -o tests/output.txt
Examples of input and output files are in tests/ folder. Please follow the same structure.
- Baldwin -> winner
- Borda -> ranking
- Condorcet -> set of winners
- Copeland -> ranking
- Dowdall -> ranking
- Kemeny Young -> ranking
- Nanson -> winner
- Pareto's check -> boolean
- Plurality -> ranking
- Raynaud -> winner
- Schulze -> ranking
- Sequential Majority Comparison -> winner
- Simpson -> ranking
- Symmetric Borda -> ranking
- Single Transferable Vote -> set of winners
The Kemeny Young method's complexity is O(n!). So, be careful with your input.