When you select a Group using a Transform (SOP) with the mouse, the group selection is based on @ptnum.
However, when you have a large number of particles in a particle simulation, you often want to reduce them to 70% using delete (SOP), and sometimes you want to reduce it to 65%.
And if you don't approve the position of some of the points, you might shift them slightly using a Transform (SOP).
In that case, you'll regret reducing the group with delete (SOP) earlier. This is because when the percentage of increase or decrease changes, the points selected by the Transform (SOP) shift to other points.
Therefore, I think it would be better if this were selected based on @id. This isn't limited to particles; it applies everywhere.
For example, you can create a Python tool like this. It's easy.
/A script tool to convert the @ptnum group of an SOP to selection by @id
//group:24,33 -> group :@id=34 @id=22
node = hou.selectedNodes()[0] geo = node.geometry() id_list = [f"@id={p.attribValue('id')}" for p in geo.globPoints(node.parm('group').eval())] node.parm('group').set(" ".join(id_list))
But it's a lot of trouble, and I wonder if there's a better way.
thanks