Linq Sum with group by

Question

我有一个带有列的表结构

FeesNormal

FeesCustom

货币

现在我正在寻找按货币计算的SUM功能组.

例如20美元+ 30欧元+ 40 INR这个表格就是这样的

如果FeesCustom> 0,我还必须考虑这个场景我必须忽略该行的FeesNormal

样本日期和预期结果是这样的

  FeesNormal  FeesCustom  Currency
  10          0            USD   
  15          25           USD //in this case can ignore FeesNormal Since FeesCustom is more
  5           10           EUR //same for this row ignore FeesNormal
  10          0            EUR

Expected result  35 USD 20 EUR   

我能够使用linq找到总和

 int sum_custom=(int)fee_list.Where(p => p.FeesCustom > 0).Sum(p => p.FeesCustom);
 int sum_normal = (int)fee_list.Where(p => p.FeesCustom ==0).Sum(p => p.FeesNormal);

Answer 1

在我看来,你只需要从"入门"到"有效费用"的预测,你可以总结 - 如:

var result = source
    .GroupBy(x => x.Currency)
    .Select(g => new {
        Currency = g.Key,
        Total = g.Sum(x => x.FeesCustom > 0 ? x.FeesCustom : x.FeesNormal)
    });

这相当于:

var result = source
    .GroupBy(x => x.Currency,
             (key, values) => new {
                Currency = key,
                Total = values.Sum(x => x.FeesCustom > 0 ? x.FeesCustom : x.FeesNormal)
             });

或者先进行转换:

 var result = source
     .Select(x => new {
         x.Currency,
         x.Fee = x => x.FeesCustom > 0 ? x.FeesCustom : x.FeesNormal
     })
     .GroupBy(x => x.Currency, x => x.Fee,
              (key, values) => new { Currency = key, Fee = values.Sum() });