Sort by attribute and reorder by vector<int> for objList?

[ylchan87]

The sort for objList in

husky/core/objlist.hpp

Lines 77 to 95 in 7ec82aa

	void sort() {
	auto& data = objlist_data_.data_;
	if (data.size() == 0)
	return;
	std::vector<int> order(this->get_size());
	for (int i = 0; i < order.size(); ++i) {
	order[i] = i;
	}
	// sort the permutation
	std::sort(order.begin(), order.end(),
	[&](const size_t a, const size_t b) { return data[a].id() < data[b].id(); });
	// apply the permutation on all the attribute lists
	for (auto& it : this->attrlist_map) {
	it.second->reorder(order);
	}
	std::sort(data.begin(), data.end(), [](const ObjT& a, const ObjT& b) { return a.id() < b.id(); });
	hashed_objs_.clear();
	sorted_size_ = data.size();
	}

now sorts with the obj.id()
Is it feasible to allow a lambda arg so a user can say sort by obj attribute?

Also, std::sort is called twice in the current implementation.

If reorder is implemented for objList and
reorder does not destroy the input permutation list (right now I think it was changed to all -1 after the call)

then we can reuse the permutation list to arrange the objList and avoid calling std::sort twice.
Would such change be feasible?

[ddmbr]

If you sort by another attribute, how do you implement ObjList::find()? I think you may want to have an extra index above the existing object list instead, but I'm not sure how to maintain this index.