index

The reverse of get item. Instead of "what's at position 3?", index answers "where is the value 42?" - it searches a data list and returns the position of the first match. Combined with the pack's get item, you can look up a value, get its position, and read it back out. That round-trip is the backbone of a lot of list-based workflow logic.

It's part of Basic data handling, StableLlama's zero-dependency utility pack.

How it works

Python's list.index(value), with the search restricted to a slice if you want it. Feed in the list and the value you're hunting; the node returns the index of the first occurrence. Two optional inputs narrow the search window:

• start (INT, default 0) - where in the list to begin looking.
• end (INT, default -1) - where to stop. The default of -1 means "to the end of the list," not "one before the end."

If the value isn't found anywhere in the window, you get -1 - Python's index() would raise an error, but this node converts that into a sentinel value you can branch on. The output index is an INT, so it wires straight into get item to re-extract the element, or into any node that wants a position.

A realistic use

Lookup-then-read is the pattern: search a list of filenames for the one containing a keyword, get its position, then use get item to pull the actual element out. Or use the -1 result as a "not present" check - the same information contains gives you, but as a number you can route anywhere.

Installing it

ComfyUI Manager → search "Basic data handling", or:

cd ComfyUI/custom_nodes
git clone https://github.com/StableLlama/ComfyUI-basic_data_handling

Restart. No dependencies, no models.

Common issues

• "I got -1 but the value is in the list." First check types - 2 (INT) and "2" (STRING) don't match. Then check start/end: if you set an end, remember it's a hard stop. And it only finds the first match, so if the value appears later after an earlier miss, that's expected.
• "The end input confused me." end is exclusive, and -1 is the special "rest of the list" value. Set it only when you genuinely want to stop early.
• "I just wanted a yes/no." Then contains is lighter weight. Index gives you the position; use the tool that matches the question.