public void Array_using_comparer_should_sort_values_correct()
{
var count = 50;
var array = new UserValueWrapper[count];
var rnd = new Random();
foreach (var i in Enumerable.Range(0, count))
{
array[i] = new UserValueWrapper(rnd.Next(1, 100), "userValue");
}
Array.Sort(array, UserValueWrapper.Comparer);
array.ToList().Select(x => x.Value).Should().BeInAscendingOrder();
}
public void Update(long value, string userValue = null)
{
long c = this.count.Increment();
if (c <= this.values.Length)
{
values[(int)c - 1] = new UserValueWrapper(value, userValue);
}
else
{
long r = NextLong(c);
if (r < values.Length)
{
values[(int)r] = new UserValueWrapper(value, userValue);
}
}
}
/// <summary>
/// Updates the sample set adding the specified value using
/// <see href="http://www.cs.umd.edu/~samir/498/vitter.pdf">Vitter's Algorithm R</see>.
/// </summary>
/// Algorithm R pseudo code
/// <example>
/// <code>
/// <![CDATA[
/// -- S has items to sample, R will contain the result
/// ReservoirSample(S[1..n], R[1..k])
/// -- fill the reservoir array
/// for i = 1 to k
/// R[i] := S[i]
/// -- replace elements with gradually decreasing probability
/// for i = k+1 to n
/// j := random(1, i) -- important: inclusive range
/// if j <= k
/// R[j] := S[i]
/// ]]>
/// </code>
/// </example>
/// <param name="value">The value to add to the sample set.</param>
/// <param name="userValue">The user value to track, which records the last, min and max user values within the sample.</param>
public void Update(long value, string userValue)
{
var c = _count.Increment();
if (c <= _values.Length)
{
_values[(int)c - 1] = new UserValueWrapper(value, userValue);
}
else
{
var r = ThreadLocalRandom.NextLong(c);
if (r < _values.Length)
{
_values[(int)r] = new UserValueWrapper(value, userValue);
}
}
}
public Snapshot GetSnapshot(bool resetReservoir = false)
{
var size = this.Size;
if (size == 0)
{
return new UniformSnapshot(0, Enumerable.Empty<long>());
}
UserValueWrapper[] values = new UserValueWrapper[size];
Array.Copy(this.values, values, size);
if (resetReservoir)
{
count.SetValue(0L);
}
Array.Sort(values, UserValueWrapper.Comparer);
var minValue = values[0].UserValue;
var maxValue = values[size - 1].UserValue;
return new UniformSnapshot(this.count.Value, values.Select(v => v.Value), valuesAreSorted: true, minUserValue: minValue, maxUserValue: maxValue);
}
public void Reset()
{
this.last = new UserValueWrapper();
this.reservoir.Reset();
}
public void Update(long value, string userValue = null)
{
this.last = new UserValueWrapper(value, userValue);
this.reservoir.Update(value, userValue);
}
/// <inheritdoc />
public void Update(long value)
{
_last = new UserValueWrapper(value);
_reservoir.Value.Update(value);
}
/// <inheritdoc />
public void Reset()
{
_last = UserValueWrapper.Empty;
_reservoir.Value.Reset();
}
public void Reset()
{
this.last = UserValueWrapper.Empty;
this.reservoir.Reset();
}
public void Reset()
{
this.last = new UserValueWrapper();
this.counter.SetValue(0L);
this.reservoir.Reset();
}
/// <inheritdoc />
public void Update(long value, string userValue)
{
_last = new UserValueWrapper(value, userValue);
_reservoir.Update(value, userValue);
}