🎲 Random String

🎲 Random String does one thing: it takes a box of newline-separated options and returns one of them. Type golden hour / overcast / neon dusk and each run picks a lighting mood. It's the smallest possible version of the wildcard idea, and sometimes that's all you want - no files, no syntax, no separate wildcard folder to manage.

It's also the node that made the randomise-your-prompt habit click for people. Everything else in a workflow gets variety - seed, steps, sampler - but the prompt text tends to get typed once and frozen, which is why so many batches look like the same picture twenty times.

How it works

input_list is split on newlines, each line is stripped, and blank lines are dropped. Then one line is picked. If nothing survives the strip - an empty box, or a box of blank lines - you get an empty string back rather than a crash, which is polite and also quietly ruins a run if you didn't notice the box is empty.

seed is optional, default -1. Set a real value and the pick is deterministic (a locally seeded RNG), which is how you get a reproducible variant: seed 7 always picks line 3, so you can compare two workflows on identical text. Leave it -1 and it draws from the unseeded RNG, i.e. different each execution - bearing in mind ComfyUI's cache, which skips nodes whose inputs didn't change. The pack's Random Seed node forces a re-run via a timestamp fingerprint; this one doesn't, so if the pick looks frozen that's why.

One thing this node does not do: substitute into a sentence. There's no {a|b|c} syntax here - the output is exactly one whole line. If you want text embedded mid-prompt, either build the line with String Concat, or move up to the pack's Wildcard Processor, which handles inline choices, weighted picks, {2$$a|b|c} multi-select, variables, file wildcards and <lora:...> tags in one go.

Inputs and outputs

Required: input_list, a multiline string, prefilled with option1 / option2 / option3 so you can see the format. Optional: seed. One output, random_choice, STRING - wire it into a CLIP Text Encode, or into String Concat if it's a fragment of a larger prompt.

Install

ComfyUI Manager → search "ComfyUI-mnemic-nodes" → install → restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/MNeMoNiCuZ/ComfyUI-mnemic-nodes

No downloads, no keys. The pack's requirements.txt (transformers, opencv-python, tiktoken, piexif, groq and friends) belongs to its other nodes; this one is plain Python.

Common issues

Blank results. Every line was empty or whitespace. Check the box.

The pick never changes. Cache or a fixed seed - set seed to -1 and change something upstream, or increment the seed yourself.

You wanted one option inside a longer prompt. Wrong node. Use the Wildcard Processor's {a|b|c} inline syntax, which is built for exactly that.

Trailing spaces behaving oddly. The node .strip()s each line, so indentation and trailing whitespace are gone by design. Don't rely on them.