public void BuildSegmentTable(int n)
{
if(_segmentTable == null) _segmentTable = new NGramCache();
foreach (var item in Documents)
{
var array = item.LanguageSegments.ToArray();
for (int i = 0; i <= array.Length - n; i++)
{
_segmentTable.Increment(array.GetNGram(i, n), 1); // inc count
}
}
}