Problem with iterating over two lists simultaniously

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I'm implementing asp.net core 3.1. I have written some code like the following and now I want to get the result of these two queries that has the same size and iterate over each one of them and divide their element and store the result in a list. But now the problem is in my zip method, I can not specify exactly which attribute of each query I want to divide.
Inside the body of foreach, r.Num and r.Denum is unknown! I appreciate of any help to fix the error.

What I have tried:

var mytotal = _context.Apiapp.GroupBy(o => new
        {
            Month = o.ApiRequestDate.Substring(4, 2),
            Year = o.ApiRequestDate.Substring(0, 4)
        }).Select(g => new
        {
            Month = g.Key.Month,
            Year = g.Key.Year,
            Total = g.Count()
        }).OrderByDescending(a => a.Year).ThenByDescending(a => a.Month).ToList();

        var numerator =  from t1 in _context.Apiapp
                         join t2 in _context.ApiAppHistory on t1.Id equals t2.ApiApplicantId
                         join t3 in _context.EntityType on t2.LastReqStatus equals t3.Id
                         where t1.IsDeleted == false && t1.LastRequestStatus == t2.Id && t3.Name == "granted"
                         group new { Year = t1.ApiRequestDate.Substring(0, 4), Month = t1.ApiRequestDate.Substring(4, 2) }
                         by new { t2.LastReqStatus } into g
                         select new
                         {
                             Year = g.Max(n => n.Year),
                             Month = g.Max(n => n.Month),
                             GrantedCount = g.Count()
                         };
        var GrantedReqStatus = numerator.ToList();
        var GrantedAccessPercent = new List<Double>();

        //-------------------------------------------------------
        var res = mytotal.Zip(GrantedReqStatus, (total, GrantedCount) => new { Num = total, Denum = GrantedCount });
        foreach(var r in res)
        {
            GrantedAccessPercent.Add(r.Num/r.Denum);
        }

Posted 2-May-20 7:31am

ElenaRez

Updated 7-May-20 8:28am

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Richard Deeming · Answer 1 · 2020-05-07T08:28:00

The error isn't that r.Num and r.Denum are unknown; the error is that the division operator isn't defined for the anonymous types.

Change your code to:

C#

var res = mytotal.Zip(GrantedReqStatus, (n, d) => new { Num = n.Total, Denum = d.GrantedCount });
foreach (var r in res)
{
    GrantedAccessPercent.Add((double)r.Num / r.Denum);
}

Or, more simply:

C#

var GrantedAccessPercent = mytotal.Zip(GrantedReqStatus, (n, d) => (double)n.Total / d.GrantedCount }).ToList();

NB: You need to cast either the numerator or the denominator to double before dividing, otherwise the result will be truncated.