public static void Rank(List <Algorithm> algorithms, string outputDirectory, double alpha = 0.05, bool maximize = false)
{
//for each measurement
for (int i = 0; i < algorithms[0].Measurements.Count; i++)
{
List <RankOutput> output = algorithms.Select(alg => new RankOutput(alg.Name, 0, 0)).ToList();
//get final iteration statistics for the current measurement
IterationStats[] stats = algorithms.Select(x => x.Measurements[i].FinalIteration).ToArray();
//perform a Kruskal-Wallis test to assess if there are differences among all the results
//double kwp = KruskalWallisTest.Calculate(stats);
//if (kwp < alpha) //significant difference exists
//{
//TODO: do I need Kruskal-Wallis? - it overflows with too many values :(
//perform a pairwise Mann-Whitney U test with Holm correction to assess individual differences
double[,] mwp = MannWhitneyUTest.PairwiseCalculate(stats);
for (int j = 0; j < mwp.GetLength(0); j++) //row
{
for (int k = 0; k < mwp.GetLength(1); k++) //col
{
//if no significant difference, move to next column
if (double.IsNaN(mwp[j, k]) || !(mwp[j, k] < alpha))
{
continue;
}
//else, compare medians to determine which algorithm was better
int rowIndex = j + 1; //note: j index starts at second algorithm (i.e., j[0] = alg[1])
int best;
int worst;
if (stats[rowIndex].Median > stats[k].Median) //alg 1 is better (assuming max)
{
best = rowIndex;
worst = k;
}
else //alg 2 is better (assuming max)
{
best = k;
worst = rowIndex;
}
if (!maximize) //swap best and worse for minimization
{
int temp = best;
best = worst;
worst = temp;
}
output[best].Wins++;
output[worst].Losses++;
}
}
//}
string rOuputDir = Path.Combine(outputDirectory, "R_output"); //directory to save output from the R script
if (!Directory.Exists(rOuputDir)) //create the output directory if it doesn't exist
{
Directory.CreateDirectory(rOuputDir);
}
//write the difference results to a CSV file
// ReSharper disable once UseStringInterpolation
using (TextWriter writer = new StreamWriter(Path.Combine(rOuputDir, string.Format("{0}_diff-{1}.csv",
algorithms[0].Measurements[i].Name,
algorithms[0].Measurements[i].FinalIteration.Iteration))))
{
writer.WriteLine("Algorithm,Wins,Losses,Difference,Rank");
foreach (RankOutput rankOutput in output.OrderBy(x => x.Algorithm))
{
int rank = output.Count(x => x.Difference > rankOutput.Difference) + 1; //this is horrible runtime, but correctly ranks the solutions
writer.WriteLine($"{rankOutput.Algorithm},{rankOutput.Wins:F0},{rankOutput.Losses:F0},{rankOutput.Difference:F0},{rank}");
}
}
}
}
public static void Rank(List <Algorithm> algorithms, string outputDirectory, double alpha = 0.05, bool maximize = false)
{
//for each measurement
for (int i = 0; i < algorithms[0].Measurements.Count; i++)
{
List <RankOutput> output = new List <RankOutput>();
foreach (Algorithm alg in algorithms)
{
output.Add(new RankOutput(alg.Name, 0, 0));
}
//get final iteration statistics for the current measurement
IEnumerable <IterationStats> stats = algorithms.Select(x => x.Measurements[i].FinalIteration);
//perform a Kruskal-Wallis test to assess if there are differences among all the results
double kwp = KruskalWallisTest.Calculate(stats);
if (kwp < alpha) //significant difference exists
{
//perform a pairwise Mann-Whitney U test with Holm correction to assess individual differences
double[,] mwp = MannWhitneyUTest.PairwiseCalculate(stats, true);
for (int j = 0; j < mwp.GetLength(0); j++) //row
{
for (int k = 0; k < mwp.GetLength(1); k++) //col
{
//there is a significant difference, comapre medians to assign best/worse
if (!double.IsNaN(mwp[j, k]) && mwp[j, k] < alpha)
{
//note: j index starts at second algorithm (i.e., j[0] = alg[1])
int rowIndex = j + 1;
int best;
int worst;
if (stats.ElementAt(rowIndex).Median > stats.ElementAt(k).Median) //alg 1 is better (assuming max)
{
best = rowIndex;
worst = k;
}
else //alg 2 is better (assuming max)
{
best = k;
worst = rowIndex;
}
if (maximize == false) //swap best and worse for minimization
{
int temp = best;
best = worst;
worst = temp;
}
output[best].Wins++;
output[worst].Losses++;
}
}
}
}
string ROuputDir = Path.Combine(outputDirectory, "R_output"); //directory to save output from the R script
if (!Directory.Exists(ROuputDir)) //create the output directory if it doesn't exist
{
Directory.CreateDirectory(ROuputDir);
}
//write the difference results to a CSV file
using (TextWriter writer = new StreamWriter(Path.Combine(ROuputDir, string.Format("{0}_diff-{1}.csv",
algorithms[0].Measurements[i].Name,
algorithms[0].Measurements[i].FinalIteration.Iteration))))
{
writer.WriteLine("Algorithm,Wins,Losses,Difference,Rank");
foreach (RankOutput rankOutput in output.OrderBy(x => x.Algorithm))
{
int rank = output.Count(x => x.Difference > rankOutput.Difference) + 1; //this is horrible runtime, but correctly ranks the solutions
writer.WriteLine($"{rankOutput.Algorithm},{rankOutput.Wins:F0},{rankOutput.Losses:F0},{rankOutput.Difference:F0},{rank}");
}
}
}
}
