Merge pull request #31 from lzear/fix-ties

Fix ties

.codacy.yaml

@@ -1,2 +1,3 @@
 exclude_paths:
   - '**/*.test.ts'
+  - 'tools/gh-pages-publish.ts'

.eslintrc.js

@@ -7,6 +7,7 @@ module.exports = {
   },
   extends: [
     'eslint:recommended',
+    'plugin:@typescript-eslint/eslint-recommended',
     'plugin:@typescript-eslint/recommended',
     'prettier',
     'prettier/@typescript-eslint',

.github/workflows/codeql-analysis.yml

@@ -3,7 +3,7 @@
 #
 # You may wish to alter this file to override the set of languages analyzed,
 # or to provide custom queries or build logic.
-name: "CodeQL"
+name: 'CodeQL'
 
 on:
   push:
@@ -29,34 +29,34 @@ jobs:
         # https://docs.github.com/en/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#overriding-automatic-language-detection
 
     steps:
-    - name: Checkout repository
-      uses: actions/checkout@v2
-
-    # Initializes the CodeQL tools for scanning.
-    - name: Initialize CodeQL
-      uses: github/codeql-action/init@v1
-      with:
-        languages: ${{ matrix.language }}
-        # If you wish to specify custom queries, you can do so here or in a config file.
-        # By default, queries listed here will override any specified in a config file. 
-        # Prefix the list here with "+" to use these queries and those in the config file.
-        # queries: ./path/to/local/query, your-org/your-repo/queries@main
-
-    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
-    # If this step fails, then you should remove it and run the build manually (see below)
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@v1
-
-    # ℹ️ Command-line programs to run using the OS shell.
-    # 📚 https://git.io/JvXDl
-
-    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
-    #    and modify them (or add more) to build your code if your project
-    #    uses a compiled language
-
-    #- run: |
-    #   make bootstrap
-    #   make release
-
-    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v1
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      # Initializes the CodeQL tools for scanning.
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v1
+        with:
+          languages: ${{ matrix.language }}
+          # If you wish to specify custom queries, you can do so here or in a config file.
+          # By default, queries listed here will override any specified in a config file.
+          # Prefix the list here with "+" to use these queries and those in the config file.
+          # queries: ./path/to/local/query, your-org/your-repo/queries@main
+
+      # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+      # If this step fails, then you should remove it and run the build manually (see below)
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@v1
+
+      # ℹ️ Command-line programs to run using the OS shell.
+      # 📚 https://git.io/JvXDl
+
+      # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+      #    and modify them (or add more) to build your code if your project
+      #    uses a compiled language
+
+      #- run: |
+      #   make bootstrap
+      #   make release
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v1

.github/workflows/coverage.yml

@@ -1,4 +1,4 @@
-name: "Code coverage"
+name: 'Code coverage'
 
 on: [push]
 
@@ -14,7 +14,10 @@ jobs:
           node-version: '12'
       - run: yarn install
       - run: yarn test
-      - run: curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
+      - run:
+          curl -L
+          https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64
+          > ./cc-test-reporter
       - run: ./tools/codacy-cov.sh
         env:
           CODACY_PROJECT_TOKEN: ${{ secrets.CODACY_PROJECT_TOKEN }}

.github/workflows/semantic-release.yml

@@ -1,8 +1,8 @@
-name: "Semantic release"
+name: 'Semantic release'
 
 on:
   push:
-    branches: [master,next]
+    branches: [master, next]
 
 jobs:
   release:

.prettierignore

@@ -0,0 +1,17 @@
+node_modules
+coverage
+.nyc_output
+.DS_Store
+*.log
+.vscode
+.idea
+dist
+compiled
+.awcache
+.rpt2_cache
+docs
+.env
+.npmrc
+
+**/*.rej
+*.rej

.prettierrc.js

@@ -3,5 +3,6 @@ module.exports = {
   tabWidth: 2,
   singleQuote: true,
   printWidth: 80,
-  "semi": false,
-};
+  proseWrap: 'always',
+  semi: false,
+}

.travis.yml

@@ -9,7 +9,8 @@ node_js:
 script:
   - npm run test:prod && npm run build
 after_success:
-  - if [ "$TRAVIS_BRANCH" = "master" -a "$TRAVIS_PULL_REQUEST" = "false" ]; then npm run travis-deploy-once "npm run deploy-docs"; fi
+  - if [ "$TRAVIS_BRANCH" = "master" -a "$TRAVIS_PULL_REQUEST" = "false" ]; then
+    npm run travis-deploy-once "npm run deploy-docs"; fi
 branches:
   except:
     - /^v\d+\.\d+\.\d+$/

README.md

@@ -14,15 +14,78 @@
 ![language](https://img.shields.io/github/languages/top/lzear/votes)
 [![license](https://img.shields.io/github/license/lzear/votes)](https://github.com/lzear/votes/blob/master/LICENSE)
 
-> Implementation of some [electoral systems](https://en.wikipedia.org/wiki/Electoral_system)
+> Implementation of some
+> [electoral systems](https://en.wikipedia.org/wiki/Electoral_system)
 
-## Install
+## 🧑‍💻 Install
 
 ```sh
-yarn install
+yarn add votes
 ```
 
+## 🗳️ Use
+
+```typescript
+import { utils as voteUtils, VotingSystem } from 'votes'
+
+const scores = scoresFromBallots(
+  [
+    { ranking: [['Lion'], ['Bear'], ['Sheep']], weight: 4 },
+    { ranking: [['Sheep'], ['Bear'], ['Lion']], weight: 3 },
+    { ranking: [['Bear', 'Sheep'], ['Lion']], weight: 2 },
+  ],
+  ['Lion', 'Bear', 'Sheep'],
+  VotingSystem.Schulze,
+)
+// -> { Lion: 0, Bear: 2, Sheep: 1 }
+
+const ranking = scoresToRanking({ Bear: 2, Lion: 0, Sheep: 1 })
+// -> [ [ 'Bear' ], [ 'Sheep' ], [ 'Lion' ] ]
+```
+
+## 📊 Voting systems
+
+See
+[Comparison of electoral systems (Wikipedia)](https://en.wikipedia.org/wiki/Comparison_of_electoral_systems)
+for more information.
+
+**Ranked pairs**: Using the duel results as edges, build an acyclic graph
+starting by the strongest score differences. The roots of the graph are the
+winners.
+
+**Schulze method**: From the votes, compute the results of all possible duels.
+Then remove the most indecisive (closest to 50/50) duels until there is an
+undefeated candidate, the winner. This popular voting system is used by several
+organizations (Ubuntu, Debian, Wikimedia...).
+
+**Kemeny–Young method**: A relatively complex computation generating a
+preference order aiming to minimize dissatisfaction of the voters. Also known as
+Kemeny rule, VoteFair popularity ranking, the maximum likelihood method, and the
+median relation.
+
+**Minimax Condorcet method**: Ranking the candidates by smallest pairwise
+defeat.
+
+**Copeland's method**: Rank candidates by number of duels won against other
+candidates.
+
+**Approval voting**: Each voter can select (“approve”) any number of candidates.
+The winner is the most-approved candidate.
+
+**Borda's count**: For each voter, every candidate is given a number of points
+which equals the number of candidates ranked lower in the voter's preference.
+
+**Instant runoff**: Considering only the top choice of each voter, the candidate
+with the fewest votes is eliminated. The election repeats until there is a
+winner. This voting system is very similar to single transferable vote method.
+
+**Two-round system**: If no candidate receives 50% of the votes in the first
+round, then a second round of voting is held with only the top two candidates.
+
+**Plurality**: Simple voting method where only the preferred candidate of each
+voter gets 1 point. AKA first-past-the-post.
+
 ## 🤝 Contributing
 
-Contributions, issues and feature requests are welcome!<br />
-Feel free to check [issues page](https://github.com/lzear/votes/issues).
+Contributions, issues and feature requests are welcome!<br /> Feel free to check
+[issues page](https://github.com/lzear/votes/issues).

package.json

@@ -21,8 +21,9 @@
   },
   "scripts": {
     "eslint": "eslint --ext .js --ext .ts .",
+    "fix:prettier": "prettier --write \"**/*.*\"",
     "prebuild": "rimraf dist",
-    "build": "tsc --module commonjs && rollup -c rollup.config.js && typedoc --exclude \"**/*.test.ts\" --out docs --target es6 --theme minimal --mode file src",
+    "build": "tsc --module commonjs && rollup -c rollup.config.js && typedoc",
     "build:watch": "tsc --module commonjs && rollup -c rollup.config.js -w",
     "test": "jest --coverage",
     "test:watch": "jest --coverage --watch",
@@ -52,33 +53,33 @@
   },
   "devDependencies": {
     "@commitlint/cli": "^11.0.0",
-    "@rollup/plugin-commonjs": "^16.0.0",
+    "@rollup/plugin-commonjs": "^17.0.0",
     "@rollup/plugin-json": "^4.1.0",
-    "@rollup/plugin-node-resolve": "^10.0.0",
-    "@types/jest": "^26.0.15",
+    "@rollup/plugin-node-resolve": "^11.0.0",
+    "@types/jest": "^26.0.16",
     "@types/lodash": "^4.14.165",
     "@types/node": "^14.14.10",
-    "@typescript-eslint/eslint-plugin": "^4.8.2",
-    "@typescript-eslint/parser": "^4.8.2",
+    "@typescript-eslint/eslint-plugin": "^4.9.0",
+    "@typescript-eslint/parser": "^4.9.0",
     "commitizen": "^4.2.2",
     "dotenv": "^8.2.0",
-    "eslint": "^7.14.0",
-    "eslint-config-prettier": "^6.15.0",
-    "eslint-plugin-prettier": "^3.1.4",
-    "husky": "^4.3.0",
+    "eslint": "^7.15.0",
+    "eslint-config-prettier": "^7.0.0",
+    "eslint-plugin-prettier": "^3.2.0",
+    "husky": "^4.3.4",
     "jest": "^26.6.3",
-    "lint-staged": "^10.5.2",
+    "lint-staged": "^10.5.3",
     "prettier": "^2.2.1",
     "rimraf": "^3.0.2",
-    "rollup": "^2.33.3",
+    "rollup": "^2.34.1",
     "rollup-plugin-sizes": "^1.0.3",
     "rollup-plugin-sourcemaps": "^0.6.3",
     "rollup-plugin-typescript2": "^0.29.0",
     "semantic-release": "^17.3.0",
     "shelljs": "^0.8.4",
     "travis-deploy-once": "^5.0.11",
     "ts-jest": "^26.4.4",
-    "ts-node": "^9.0.0",
+    "ts-node": "^9.1.0",
     "typedoc": "^0.19.2",
     "typescript": "^4.1.2"
   },

src/methods/approbation/index.ts

@@ -1,26 +1,14 @@
-import zipObject from 'lodash/zipObject'
 import {
   SystemUsingRankings,
   ScoreObject,
   VotingSystem,
   Ballot,
 } from '../../types'
+import { iterateFirstChoices } from '../first-past-the-post'
 
 export const approbation: SystemUsingRankings = {
   type: VotingSystem.Approbation,
   computeFromBallots(ballots: Ballot[], candidates: string[]): ScoreObject {
-    const result: ScoreObject = zipObject(
-      candidates,
-      new Array(candidates.length).fill(0),
-    )
-    ballots.forEach((ballot) => {
-      if (ballot.ranking.length) {
-        const votes = ballot.ranking[0].filter((c) => candidates.includes(c))
-        votes.forEach((v) => {
-          result[v] += ballot.weight
-        })
-      }
-    })
-    return result
+    return iterateFirstChoices(ballots, candidates, () => 1)
   },
 }

src/methods/borda/index.ts

@@ -1,18 +1,15 @@
-import zipObject from 'lodash/zipObject'
 import {
   SystemUsingRankings,
   ScoreObject,
   VotingSystem,
   Ballot,
 } from '../../types'
+import { scoresZero } from '../../utils/scoresZero'
 
 export const borda: SystemUsingRankings = {
   type: VotingSystem.Borda,
   computeFromBallots(ballots: Ballot[], candidates: string[]): ScoreObject {
-    const result: ScoreObject = zipObject(
-      candidates,
-      new Array(candidates.length).fill(0),
-    )
+    const result: ScoreObject = scoresZero(candidates)
     ballots.forEach((ballot) => {
       let voteValue = candidates.length - 1
       ballot.ranking.forEach((candidatesAtRank) => {