kopia lustrzana https://github.com/martinlackner/apportionment
79 wiersze
3.2 KiB
Markdown
79 wiersze
3.2 KiB
Markdown
[](https://doi.org/10.5281/zenodo.6108968)
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[](https://choosealicense.com/licenses/mit/)
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[](https://pypi.org/project/apportionment/)
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[](https://github.com/martinlackner/apportionment/actions)
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[](https://github.com/martinlackner/apportionment/actions)
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# A Python implementation of common apportionment methods
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This is a collection of common apportionment methods. Apportionment has two main applications:
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to assign a fixed number of [parliamentary seats to parties](https://en.wikipedia.org/wiki/Party-list_proportional_representation) (proportionally to their vote count), and to assign
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[representatives in a senate to states](https://en.wikipedia.org/wiki/United_States_congressional_apportionment) (proportionally to their population count).
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A recommendable overview of apportionment methods can be found in the book "Fair Representation" by Balinski and Young [2].
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The following apportionment methods are implemented:
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* the largest remainder method (or Hamilton method)
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* the class of divisor methods including
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- D'Hondt (or Jefferson)
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- Sainte-Laguë (or Webster)
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- Modified Sainte-Laguë (as used e.g. in Norway)
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- Huntington-Hill
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- Adams
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* the quota method [1]
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## Installation
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Using pip:
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```bash
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pip install apportionment
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```
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Latest development version from source:
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```bash
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git clone https://github.com/martinlackner/apportionment/
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python setup.py install
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```
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Requirements:
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* Python 3.7+
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* numpy
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## A simple example
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The following example calculates the seat distribution of Austrian representatives in the
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European Parliament based on the D'Hondt method and the [2019 election results](https://www.bmi.gv.at/412/Europawahlen/Europawahl_2019). Parties that received less than 4% are excluded from obtaining seats and are thus excluded in the calculation.
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```python
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import apportionment.methods as app
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parties = ['OEVP', 'SPOE', 'FPOE', 'GRUENE', 'NEOS']
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votes = [1305956, 903151, 650114, 532193, 319024]
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seats = 18
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app.compute("dhondt", votes, seats, parties, verbose=True)
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```
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The output is
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```
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D'Hondt (Jefferson) method
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OEVP: 7
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SPOE: 5
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FPOE: 3
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GRUENE: 2
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NEOS: 1
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```
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which is indeed the [official result](https://www.bmi.gv.at/412/Europawahlen/Europawahl_2019).
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Another example can be found in [examples/simple.py](examples/simple.py).
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We verify results from recent Austrian National Council elections in [examples/austria.py](examples/austria.py) and from recent elections of the Israeli Knesset in [examples/israel.py](examples/israel.py).
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## References
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[1] Balinski, M. L., & Young, H. P. (1975). The quota method of apportionment. The American Mathematical Monthly, 82(7), 701-730.
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[2] Balinski, M. L., & Young, H. P. (1982). Fair Representation: Meeting the Ideal of One Man, One Vote. Yale University Press, 1982. (There is a second edition from 2001 by Brookings Institution Press.)
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