Google Apps Script

github.com/haya14busa/gas-openskill

gas-openskill is a Google Apps Script library wrapping the openskill algorithm. It's the easiest way to keep skill ratings inside a Google Sheet or Google Workspace add-on.

There's also a companion Google Sheets template if you want a no-code starting point.

Install

In the Apps Script editor:

Open Project Settings and copy the script ID from the gas-openskill repo.
Click Libraries → +, paste the script ID, pick the latest version, and set the identifier to Openskill.

Idiomatic usage

function rateMatch() {
  // 1. Create ratings — Apps Script tip: persist mu/sigma in the sheet,
  //    not the Rating object, since runs don't share state.
  const a1 = Openskill.rating()                                     // mu=25, sigma≈8.333
  const a2 = Openskill.rating({ mu: 32.444, sigma: 5.123 })
  const b1 = Openskill.rating({ mu: 43.381, sigma: 2.421 })
  const b2 = Openskill.rating({ mu: 25.188, sigma: 6.211 })

  // 2. Team A beats Team B
  const [[a1n, a2n], [b1n, b2n]] = Openskill.rate([
    [a1, a2],
    [b1, b2],
  ])

  // 3. Write the new ratings back into the sheet
  const sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Players')
  sheet.getRange('B2:C2').setValues([[a1n.mu, a1n.sigma]])
  sheet.getRange('B3:C3').setValues([[a2n.mu, a2n.sigma]])
  sheet.getRange('B4:C4').setValues([[b1n.mu, b1n.sigma]])
  sheet.getRange('B5:C5').setValues([[b2n.mu, b2n.sigma]])
}

Custom function for a Sheet

Expose ordinal as a custom spreadsheet function so cells can show a single sortable number.

/**
 * @param {number} mu
 * @param {number} sigma
 * @return number  Skill ordinal (mu - 3*sigma).
 * @customfunction
 */
function ORDINAL(mu, sigma) {
  return Openskill.ordinal({ mu: mu, sigma: sigma })
}

Then in any cell: =ORDINAL(B2, C2).