Say I have a mesh who's shape is quite irregular, but the topology is very regular (all-quads).

Now I have a group consists of a face loop or edge loop:



My question is how could I expand it toward an "end"? Like this:



I notice that it's surprisingly easy to do it manually: just press Shift+H and click a face, and Houdini'll floodfill the selection. But how could I do this procedurally? What's this "H" hotkey's procedural counterpart (like a vex floodfill vex function or something?)

raincole
What's this "H" hotkey's procedural counterpart

it's called Group Expand SOP

where you can specify your Base Group, which is the face you "clicked"
Collision Group, which is your initially selected ring in first picture
and check Flood Fill to Connected Geometry