/// <summary>
/// Swap two items, across all divisions.
/// </summary>
/// <param name="dataDivisionList">The division list.</param>
/// <param name="a">The index of the first item to swap.</param>
/// <param name="b">The index of the second item to swap.</param>
private void VirtualSwap(IEnumerable <DataDivision> dataDivisionList, int a, int b)
{
DataDivision divA = null;
DataDivision divB = null;
int offsetA = 0;
int offsetB = 0;
// Find points a and b in the collections.
int baseIndex = 0;
foreach (DataDivision division in dataDivisionList)
{
baseIndex += division.Count;
if (divA == null && a < baseIndex)
{
divA = division;
offsetA = a - (baseIndex - division.Count);
}
if (divB == null && b < baseIndex)
{
divB = division;
offsetB = b - (baseIndex - division.Count);
}
}
// Swap a and b.
int temp = divA.Mask[offsetA];
divA.Mask[offsetA] = divB.Mask[offsetB];
divB.Mask[offsetB] = temp;
}
/// <summary>
/// Generate the counts for all divisions, give remaining items to final division.
/// </summary>
/// <param name="dataDivisionList">The division list.</param>
/// <param name="totalCount">The total count.</param>
private void GenerateCounts(IList <DataDivision> dataDivisionList,
int totalCount)
{
// First pass at division.
int countSofar = 0;
foreach (DataDivision division in dataDivisionList)
{
var count = (int)(division.Percent * totalCount);
division.Count = count;
countSofar += count;
}
// Adjust any remaining count
int remaining = totalCount - countSofar;
while (remaining-- > 0)
{
int idx = _rnd.NextInt(dataDivisionList.Count);
DataDivision div = dataDivisionList[idx];
div.Count = div.Count + 1;
}
}
