hey guys i was trying to figure out how can i add a joint skeleton to the hierarchy using graph script?
thanks in advance

I'm not sure what you mean by "graph script" since the APEX Edit Graph SOP doesn't support scripting? In APEX, you should be able to modify a skeleton using the skel:: nodes like skel::AddJoint and then wire it in using skel::SetParent(s)

its not working... no joint is added.
can u give me a hip file example please?

I think you're missing some pieces here. The "character" geometry is the entire packed folder geometry.
ExtractCharacterGraph extracts out a "graph" (aka "rig") from the "character" input and just pipes it pack out for convenience so that you can chain things along. ExtractCharacterGraph isn't modifying the "character" at all.

Adding a joint to the character geometry is basically trying to add a joint to the geometry of your "packfolder1" SOP. That clearly cannot work. You can use the FindCharacterElement and UpdateCharacterElement nodes to unpack the skeleton, manipulate it, and then put it back in. If you dive inside these nodes (which are actually subgraphs), you'll see that they're just convenience wrappers on top of sop::unpackfolder and sop::packfolder. In any case, I built a very basic example in the attached hip file (saved in Houdini 20.0.634). In practice, you might be looking to do more of course, but hope that helps!

ahhhh i see thank u...

best regards
Patar