How to create a custom column which is a function of other results?

[quixoticaxis]

Hello.

I'm trying to implement a simple custom column that would contain Mean / N value where mean is a mean time from the standard result attributes, and N is a custom parameter that controls the number of iterations inside of my benchmark.
I understand how to get the value of N for a custom column, but I can't seem to find how to get the Mean value.

[leonvandermeer]

In the GetValue implementation of your column, you can get to the the parameter's value and benchmark's statistics like so:

public string GetValue(Summary summary, BenchmarkCase benchmarkCase, SummaryStyle style) {
  int n = (int)benchmarkCase.Parameters["N"];
  Statistics statistics = summary[benchmarkCase]!.ResultStatistics!;
  double mean = TimeInterval.FromNanoseconds(statistics.Mean).ToSeconds();
  double result = mean / n;
  return string.Create(style.CultureInfo, $"{result:F3} s");
}

In another column, you can calculate the error, assuming the error of N is zero:

double result = ...; double mean = ...; as above
double meanStdDev = TimeInterval.FromNanoseconds(statistics.StandardDeviation).ToSeconds();
double resultStdDev = result * meanStdDev / mean;
return string.Create(style.CultureInfo, $"{resultStdDev:F3} s");

[quixoticaxis]

Thank you.