Method _getParticlesByColumn

external/.scrollLibs.js:15851–15853

(index, name)

    return this.find(particle => particle.getAtom(index) === name)
  }
  _getParticlesByColumn(index, name) {
    return this.filter(particle => particle.getAtom(index) === name)
  }
  // todo: preserve subclasses!
  select(columnNames) {
    columnNames = Array.isArray(columnNames) ? columnNames : [columnNames]