如何计算mongo集合中具有相交子集合的项？

db.collection.aggregate([
  { $unwind: "$subset" },
  {
    $group: {
      _id: "$_id",
      parentField: { $first: "$parentField" },
      intersectedSubset: { $push: "$subset" }
    }
  },
  {
    $project: {
      _id: 0,
      parentField: 1,
      intersectedSubset: {
        $filter: {
          input: "$intersectedSubset",
          as: "subset",
          cond: { $gt: [{ $size: { $setIntersection: ["$intersectedSubset", "$$subset"] } }, 1] }
        }
      }
    }
  }
])