/// <summary>
/// Gets the items with the highest values from <paramref name="statisticsResult"/>.
///
/// This will return at least <paramref name="atLeast"/> items whose value exceeds <paramref name="minSampleValue"/> (if available).
/// It will try to return all 'equal best' items (ie items in the same bucket) but only up to <paramref name="noMoreThan"/>.
/// </summary>
public static IEnumerable <T> GetTopItems <T>(this DiscreteStatisticsResult <T> statisticsResult, int atLeast, int noMoreThan, int minSampleValue = int.MinValue)
{
atLeast = Min(atLeast, statisticsResult.ItemsCount);
noMoreThan = Min(noMoreThan, statisticsResult.ItemsCount);
var itemsReturned = 0;
for (int i = statisticsResult.BucketValues.Count - 1; i >= 0; i--)
{
if (itemsReturned >= atLeast)
{
break;
}
var bucketValue = statisticsResult.BucketValues[i];
if (bucketValue < minSampleValue)
{
break;
}
var bucket = statisticsResult.ItemsByBucket[bucketValue];
foreach (var item in bucket)
{
if (itemsReturned >= noMoreThan)
{
break;
}
yield return(item);
itemsReturned++;
}
}
}
public void When_Simple()
{
var rawValues = new[] { 12, 1, 5, 7, 5, 8, -4, 5, 1, 22, 5, 1, 8 };
var values = rawValues.Select(i => new SimpleWrapper(i)).ToArray();
var mean = (double)rawValues.Sum() / rawValues.Count();
var min = -4;
var max = 22;
var mode = 5;
var sortedDistinct = rawValues.Distinct().OrderBy(i => i).ToArray();
var statisticsResult = DiscreteStatisticsResult.Create(values, v => v.Value);
Assert.AreEqual(min, statisticsResult.Min);
Assert.AreEqual(max, statisticsResult.Max);
Assert.AreEqual(mode, statisticsResult.Mode);
Assert.AreEqual(mean, statisticsResult.Mean);
var index = -1;
foreach (var bucket in statisticsResult.BucketValues)
{
index++;
Assert.AreEqual(sortedDistinct[index], bucket);
}
Assert.AreEqual(4, statisticsResult.Histogram[5]);
Assert.AreEqual(0, statisticsResult.Histogram[6]);
Assert.IsFalse(statisticsResult.Histogram.ContainsKey(23));
Assert.IsTrue(statisticsResult.Histogram.ContainsKey(20));
}
public void When_Simple_BucketSD()
{
var rawValues = new[] { 11, 11, 11, 12, 14, 14 };
var values = rawValues.Select(i => new SimpleWrapper(i)).ToArray();
const double expectedSD = 1.1180339887499; // https://www.calculator.net/standard-deviation-calculator.html?numberinputs=3%2C+1%2C+0%2C+2&ctype=p&x=48&y=24
var statisticsResult = DiscreteStatisticsResult.Create(values, v => v.Value);
Assert.AreEqual(expectedSD, statisticsResult.SDBucketCount, delta: 1e-6);
}
public void When_Bucket_Counts()
{
var rawValues = new[] { 11, 11, 11, 12, 14, 14 };
var values = rawValues.Select(i => new SimpleWrapper(i)).ToArray();
var statisticsResult = DiscreteStatisticsResult.Create(values, v => v.Value);
Assert.AreEqual(4, statisticsResult.Histogram.Count);
Assert.AreEqual(3, statisticsResult.MaxBucketCount);
Assert.AreEqual(0, statisticsResult.MinBucketCount);
Assert.AreEqual(1.5, statisticsResult.MeanBucketCount);
}
