utility function for NEAT crossover

getCombinedConnections.js

function getCombinedConnections(n1conns, n2conns, score1, score2, equal) {
  // Split common conn genes from disjoint or excess conn genes

  const keys1 = Object.keys(n1conns)
  const keys2 = Object.keys(n2conns)
  const commonKeys = keys1.filter(key => n2conns[key] !== undefined)
  const commonConns = commonKeys.map(key => n1conns[key])

  const other1Keys = keys1.filter(key => commonKeys.includes(key) === false)
  const other2Keys = keys2.filter(key => commonKeys.includes(key) === false)

  if (other1Keys.length === 0 && other2Keys.length === 0) return commonConns

  const extraKeys = []

  if (score1 >= score2 || equal) {
    extraKeys.push(...other1Keys.filter(key => n2conns[key] === undefined)) // Excess/disjoint gene
  }

  if (score2 >= score1 || equal) {
    extraKeys.push(...other2Keys.filter(key => n2conns[key] !== undefined)) // Excess/disjoint gene
  }

  const extraConns = extraKeys.map(key => n1conns[key] || n2conns[key])

  return [...commonConns, ...extraConns].map(Number)
}