private static void MinMax_Inner(UniformDistributionSampler sampler, int len)
{
// Alloc arrays and fill with uniform random noise.
float[] a = new float[len];
sampler.Sample(a);
// Calc results and compare.
PointwiseMinMax(a, out float expectedMin, out float expectedMax);
MathSpan.MinMax(a, out float actualMin, out float actualMax);
Assert.Equal(expectedMin, actualMin, 10);
Assert.Equal(expectedMax, actualMax, 10);
}
private static void MinMax_Inner(ISampler <int> sampler, int len)
{
// Alloc arrays and fill with uniform random noise.
int[] a = new int[len];
sampler.Sample(a);
// Calc results and compare.
PointwiseMinMax(a, out int expectedMin, out int expectedMax);
MathSpan.MinMax(a, out int actualMin, out int actualMax);
Assert.Equal(expectedMin, actualMin);
Assert.Equal(expectedMax, actualMax);
}
/// <summary>
/// Calculate a histogram for the provided span of values.
/// 1) The minimum and maximum values are found.
/// 2) The resulting value range is divided into equal sized sub-ranges or bins.
/// 3) The number of values that fall into each bin is determined.
/// </summary>
/// <param name="vals">The values to calculate a histogram for.</param>
/// <param name="binCount">The number of histogram bins to use.</param>
/// <returns>A new instance of <see cref="HistogramData"/>.</returns>
public static HistogramData BuildHistogramData(Span <double> vals, int binCount)
{
// Determine min/max.
MathSpan.MinMax(vals, out double min, out double max);
// Note. each bin's range has interval [low,high), i.e. samples exactly equal to 'high' will fall
// into the next highest bin. Except for the last bin which has interval [low, high].
double range = max - min;
// Handle special case where the data series contains a single value.
if (range == 0.0)
{
return(new HistogramData(min, max, 0.0, new int[] { vals.Length }));
}
// Loop values, and for each one increment the relevant category's frequency count.
double incr = range / binCount;
int[] frequencyArr = new int[binCount];
for (int i = 0; i < vals.Length; i++)
{
// Determine which bin the value falls within.
int binIdx = (int)((vals[i] - min) / incr);
// Values that equal max, are placed into the last bin.
if (binIdx == binCount)
{
binIdx--;
}
frequencyArr[binIdx]++;
}
return(new HistogramData(min, max, incr, frequencyArr));
}
