掺杂质量计算的python脚本

起因是我想合成各式各样的材料，需要用到各种药品，计算起来比较麻烦，尤其是非化学计量比的化合物比如$\mathrm{Li_{5.3}PS_{4.3}Cl_{0.7}Br}$，遂用AI写了一个python脚本，个人觉得还是比较实用

from decimal import Decimal, getcontext
import re
from sympy import symbols, Eq, solve, nsimplify

getcontext().prec = 100  # 设置100位高精度计算

class FormulaParser:
    @staticmethod
    def parse(formula: str) -> dict:
        """解析化学式返回元素组成字典"""
        elements = {}
        pattern = re.compile(r"([A-Z][a-z]?)([\d.]*)?")
        index = 0

        while index < len(formula):
            match = pattern.match(formula, index)
            if not match:
                raise ValueError(f"无效化学式格式：{formula[index:]}")

            elem = match.group(1)
            number = match.group(2)

            if number == '':
                coeff = Decimal(1)
            else:
                try:
                    coeff = Decimal(number)
                except:
                    raise ValueError(f"无效系数：{number}")

            if elem in elements:
                raise ValueError(f"重复元素：{elem}")

            elements[elem] = coeff
            index = match.end()

        return elements

class SynthesisCalculator:
    def __init__(self):
        self.target = {}
        self.reagents = []
        self.molar_masses = []

    def input_target(self):
        formula = input("请输入目标化学式（例如Li5.3PS4.3Cl0.7Br）: ").strip()
        self.target = FormulaParser.parse(formula)
        print(f"已解析目标化合物: {self.target}")

    def input_reagents(self):
        num = int(input("请输入原料种数: "))
        for i in range(num):
            formula = input(f"原料{i+1}化学式: ").strip()
            try:
                parsed = FormulaParser.parse(formula)
                self.reagents.append(parsed)
                mm = Decimal(input(f"原料{i+1}摩尔质量（g/mol）: ").strip())
                self.molar_masses.append(mm)
            except Exception as e:
                print(f"输入错误: {e}")
                exit()

    def validate_elements(self):
        target_elements = set(self.target.keys())
        provided = set()
        for r in self.reagents:
            provided.update(r.keys())
        missing = target_elements - provided
        if missing:
            print(f"错误：缺少以下元素: {', '.join(missing)}")
            exit()

    def build_equations(self, n: Decimal):
        variables = symbols(f'x0:{len(self.reagents)}')
        equations = []

        for element, coeff in self.target.items():
            lhs = sum(
                var * Decimal(str(reagent.get(element, 0.0)))
                for var, reagent in zip(variables, self.reagents)
            )
            equations.append(Eq(lhs, coeff * n))

        return variables, equations

    def solve(self, n: Decimal):
        variables, equations = self.build_equations(n)
        try:
            solution = solve(equations, variables, dict=True)
            if not solution:
                print("无可行解：原料配比无法满足目标成分")
                exit()
            # 将解转换为Decimal
            decimal_solution = []
            for sol in solution:
                new_sol = {}
                for k, v in sol.items():
                    # 将Sympy数值转换为字符串再转为Decimal
                    new_sol[k] = Decimal(str(nsimplify(v).evalf(50)))
                decimal_solution.append(new_sol)
            return decimal_solution
        except Exception as e:
            print(f"求解错误: {e}")
            exit()

    def calculate(self):
        n = Decimal(input("请输入目标物质的量（mol）: ").strip())
        solution = self.solve(n)[0]  # 取第一组解

        print("\n" + "="*60)
        print(f"合成 {n} mol 目标化合物需要:")

        total_mass = Decimal(0)
        for i, (var, moles) in enumerate(solution.items()):
            if moles < 0:
                print(f"错误：{var} 的摩尔量为负值")
                exit()

            mass = moles * self.molar_masses[i]
            total_mass += mass

            print(f"原料{i+1}:")
            print(f"  化学式: {self.reagents[i]}")
            print(f"  需要量: {moles.normalize():.50f} mol")
            print(f"  质量: {mass.normalize():.50f} g\n")

        print(f"总质量: {total_mass.normalize():.50f} g")

def main():
    print("高精度化合物合成计算器")
    print("="*60)

    calc = SynthesisCalculator()
    calc.input_target()
    calc.input_reagents()
    calc.validate_elements()
    calc.calculate()

if __name__ == "__main__":
    main()

附一张使用截图，后面也会放到Github上面