otter.parse_formula_composition

otter.parse_formula_composition(formula: str) → tuple[list[str], list[float]][source]

Parse one simple chemical formula into distinct species and counts.

Parameters:: formula – Chemical formula such as Al, CH2, or C10H8O4.
Returns:: list[str], list[float] – Distinct species symbols and their stoichiometric counts.

Notes

This parser intentionally targets the compact formulas used by the current AA/mixture workflows. Parentheses and charge annotations are rejected. Repeated symbols are accumulated while preserving first appearance order, so structural formulas such as CH3COOH become C2H4O2.