I have a for-loop, driven by its iteration count, that feeds back onto itself for many iterations. I want to save a geo sequence for each iteration stage. My current plan: 1) plug a geometry ROP to the output of the loop, 2) inside the loop, jut before the output, insert a Python node that triggers the ROP's "Save" button. If there are better approaches, please let me know

put $F in the iteration value. Then write a cache sequence with the same length to disk. done.

Cheers
CYTE

CYTE
put $F in the iteration value

I tried it first, but it's inefficient. If I save a frame range to a File Cache from the loop's output, on each frame, the for-loop starts from the very beginning. E.g. on frame 10, it goes through 9 iterations: 1-9. I want the for-loop to run only once, efficiently, saving a geo for each iteration.

You can use File SOP inside of your loop
Set to Write mode with filename dependent on your iteration
Then you should be able to write out a sequence per each iteration

If however you just want a single sequence when each iteration is a frame then Solver SOP may be more convenient

Not 100% sure what you're doing, but I'd recommend looking into TOPs, it has a For-Loop With Feedback top. If I'm not mistaken, Entagma did a paid course on it "PDG 101 – Pt.16: Feedback Loops" where they rendered out an image and fed it back to the loop as a texture. SOP and TOP for-loops could have virtually identical results, but a sop for-loop will most likely freeze your houdini without any info on how things are going. PDG is the way to go whenever exporting and re-importing anything.

Edit: gave it a shot out of curiosity. Attaching a hip.
Edit2: Attaching an second hip that supports an animated sequence.