Function groupSimilarity

packages/tools/api-diff/src/Diff.ts:110–155

(
  base: ApiGroup,
  head: ApiGroup
)

const groupName = (group: ApiGroup): string => group.path.at(-1) ?? ""

const groupSimilarity = (
  base: ApiGroup,
  head: ApiGroup
): number => {
  const facets = base.entities.flatMap((baseEntity) => {
    const headEntity = head.entities.find((candidate) => candidate.bucket === baseEntity.bucket)
    return headEntity === undefined ? [] : [{ base: baseEntity, head: headEntity }]
  })
  if (facets.length === 0) {
    return 0
  }
  const sameKind = facets.filter(({ base, head }) => base.declarationKind === head.declarationKind).length /
    facets.length
  const sameFingerprint = facets.filter(({ base, head }) => base.fingerprint === head.fingerprint).length /
    facets.length
  const structure = facets.reduce(
    (total, { base, head }) => total + setSimilarity(entityFeatures(base), entityFeatures(head)),
    0
  ) / facets.length
  const documentation = facets.reduce(
    (total, { base, head }) => total + setSimilarity(documentationTokens(base), documentationTokens(head)),
    0
  ) / facets.length
  const sameCategory = facets.some(({ base, head }) =>
    base.documentation.category !== undefined &&
    base.documentation.category === head.documentation.category
  )
  const headModuleName = head.module.split("/").at(-1)?.toLowerCase()
  const mentionsHeadModule = headModuleName !== undefined &&
    facets.some(({ base }) => documentationTokens(base).has(headModuleName))
  const moduleScore = base.module === head.module ? 0.25 : 0
  const packageScore = base.entities[0]!.packageName === head.entities[0]!.packageName ? 0.05 : 0
  return Math.min(
    0.99,
    0.2 * nameSimilarity(groupName(base), groupName(head)) +
      (groupName(base) === groupName(head) ? 0.15 : 0) +
      moduleScore +
      packageScore +
      0.4 * sameFingerprint +
      0.15 * sameKind +
      0.15 * structure +
      0.025 * documentation +
      (sameCategory ? 0.05 : 0) +
      (mentionsHeadModule ? 0.075 : 0)
  )
}

const changeId = (
  classification: ChangeClassification,