python—在满足某个floatvalue之前，从浮点池中减去浮点的最佳方法是什么

baubqpgj 于 2021-07-13 发布在 Java

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我试图从一个值池中减去值，直到满足某个值为止，我应该如何做才能最小化舍入误差？这个代码的明显问题是+/-0.0001它永远不会是精确的。。。有没有一种方法可以在python中正确地做到这一点？

for budgettodistributeto in budgetstodistributeto:
            amountneeded = (Decimal(budgettodistributeto.forcepercentageofbudget) -
                            Decimal(campaignidpercentagedict[budgettodistributeto.campaignid])
                            / totalpercentageforday)
            assert (amountneeded > 0.0)
            currentamount = 0
            while currentamount < amountneeded:
                for budgettoretrievefrom in budgetstoretrievefrom:
                    if (Decimal(budgettoretrievefrom.forcepercentageofbudget) <=
                            ((Decimal(campaignidpercentagedict[budgettoretrievefrom.campaignid])
                              / totalpercentageforday) - Decimal(0.001))):
                        daybudgetcampaigndictcopied[day][budgettoretrievefrom.campaignid] -= Decimal(0.001)
                        currentamount += Decimal(0.001)
            daybudgetcampaigndictcopied[day][budgettodistributeto.campaignid] += amountneeded
        daybudgetcampaigndictcopied[day] = campaignidpercentagedict

python python-3.x Precision Decimal floating-point

来源：https://stackoverflow.com/questions/67283579/which-is-the-best-way-to-subtract-a-float-from-a-pool-of-floats-until-a-certain

1条答案

按热度按时间

omvjsjqw1#

我将按以下方式处理这个问题：


# Function to detect if current value is within the desired accuracy
def in_range(cur_val: float, tgt_val: float, tol:float) -> bool:
    if cur_val >= tgt_val - tol and cur_val <= tgt_val + tol:
        return True
    return False

一种循环，通过某种方式减少池值，直到in0 range函数为真，如下所示：

while not in_range(pool, budget, accuracy) and pool > budget + accuracy:
    pool -= (pool - budget)*dec_amt
    print(pool)
print(Decimal(pool).quantize(Decimal('.01')))

当然，你将不得不应用你自己的逻辑部分，你正在寻找所需的价值。

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python—在满足某个floatvalue之前，从浮点池中减去浮点的最佳方法是什么

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