Generalised n:m splitter
Splits the input into a ratio of n/(n+m) and m/(n+m), where n is the left in/output, and m is the right in/output.
For reference, a regular splitter is a 1:1 splitter.
Only guaranteed to work with fully saturated input

Originally shared on the public FactorioPrints / Factorio School archive (factorioprints.com · factorio.school). Authorship preserved from the public catalog.
Generalised n:m splitter
Splits the input into a ratio of n/(n+m) and m/(n+m), where n is the left in/output, and m is the right in/output.
For reference, a regular splitter is a 1:1 splitter.
Only guaranteed to work with fully saturated input