protected virtual bool ContainsKey(TKey key, int hash, bool validate)
{
if (validate && ValidateConfiguration)
{
IsValidConfiguration(Configuration.IdHash(key), hash);
}
return(_configuration
.Probe(BlockSize, _hashFunctionCount, hash)
.All(position => _data.Get((int)position)));
}
public void Test_Set_Get()
{
uint [] bitCounts = { 0, 1, 3, 100, 1000 };
for (int run = 0; run < bitCounts.Length; ++run)
{
uint bitCount = bitCounts[run];
FastBitArray fba = new FastBitArray(bitCount);
// Fill with a pattern 1111...
for (uint i = 0; i < bitCount; ++i)
{
fba.Set(i, true);
}
// Verify
for (uint i = 0; i < bitCount; ++i)
{
Assert.AreEqual(true, fba.Get(i));
}
// Fill with a pattern 00000...
for (uint i = 0; i < bitCount; ++i)
{
fba.Set(i, false);
}
// Verify
for (uint i = 0; i < bitCount; ++i)
{
Assert.AreEqual(false, fba.Get(i));
}
// Fill with a pattern 010101...
for (uint i = 0; i < bitCount; ++i)
{
fba.Set(i, i % 2 == 0);
}
// Verify
for (uint i = 0; i < bitCount; ++i)
{
Assert.AreEqual(i % 2 == 0, fba.Get(i));
}
// Fill with a pattern 101010...
for (uint i = 0; i < bitCount; ++i)
{
fba.Set(i, i % 2 == 1);
}
// Verify
for (uint i = 0; i < bitCount; ++i)
{
Assert.AreEqual(i % 2 == 1, fba.Get(i));
}
}
}
/// <summary>
/// Compute similarity between <paramref name="minHashValues1"/> and <paramref name="minHashValues2"/>
/// </summary>
/// <param name="minHashValues1">The values</param>
/// <param name="minHashValues2">The values to compare against</param>
/// <param name="numHashFunctions">The number of hash functions to use</param>
/// <param name="bitSize">The number of bits for a single cell</param>
/// <returns></returns>
private static double?ComputeSimilarityFromSignatures(
FastBitArray minHashValues1,
FastBitArray minHashValues2,
int numHashFunctions,
byte bitSize)
{
if (minHashValues1 == null ||
minHashValues2 == null ||
numHashFunctions <= 0 ||
bitSize == 0)
{
return(0.0D);
}
if (minHashValues1.Length != minHashValues2.Length)
{
return(null);
}
uint identicalMinHashes = 0;
var bitRange = Enumerable.Range(0, bitSize).ToArray();
var minHash1Length = minHashValues1.Length / bitSize;
var idx1 = 0;
for (var i = 0; i < minHash1Length; i++)
{
if (bitRange
.All(b => minHashValues1.Get(idx1 + b) == minHashValues2.Get(idx1 + b)))
{
identicalMinHashes++;
}
idx1 += bitSize;
}
return(identicalMinHashes / (1.0D * minHashValues2.Length / bitSize));
}
public void Benchmark_Read()
{
uint BIT_COUNT = 100000000;
int REP_COUNT = 10;
FastBitArray ba = new FastBitArray(BIT_COUNT);
// Fill with a pattern 0101...
for (uint i = 0; i < BIT_COUNT; ++i)
{
ba.Set(i, (i % 2) == 0);
}
bool checksum = false;
var startTime = DateTime.Now;
for (int r = 0; r < REP_COUNT; ++r)
{
for (uint i = 0; i < BIT_COUNT; ++i)
{
checksum ^= ba.Get(i);
}
}
var runTime = (DateTime.Now - startTime).TotalSeconds;
double totalBitCount = (double)REP_COUNT * BIT_COUNT;
Console.WriteLine("Reading bits: count: {0:#,#}, time: {1:0.000} s, {2:#,#} b/s, cs: {0}",
totalBitCount, runTime, totalBitCount / runTime, checksum);
}
private static bool GetFolded(FastBitArray bitArray, int position, uint foldFactor)
{
if (foldFactor == 1)
{
return(bitArray[position]);
}
var foldedSize = bitArray.Length / foldFactor;
for (var i = 0; i < foldFactor; i++)
{
if (bitArray.Get(position + i * (int)foldedSize))
{
return(true);
}
}
return(false);
}
/// <summary>
/// Get all the primes at most equal to <param name="to"></param>
/// </summary>
/// <param name="to"></param>
/// <returns>All primes up to <paramref name="to"/>.</returns>
internal static IEnumerable <long> GetPrimes(long to)
{
var cached = _primeCache;
if (cached != null && cached.Item1 >= to)
{
return(cached.Item2.Where(p => p <= to).ToArray());
}
var sieveContainer = new FastBitArray((int)to + 1, true);
int marker = 2; //start
sieveContainer[0] = false; //0 is not prime
sieveContainer[1] = false; //1 is not prime
while (marker * marker <= sieveContainer.Length)
{
var factor = marker;
while ((factor += marker) <= to)
{
sieveContainer[factor] = false;
}
while (!sieveContainer.Get(++marker))
{
}
}
var primes = new List <long>();
for (var i = 0; i < sieveContainer.Length; i++)
{
if (sieveContainer[i])
{
primes.Add(i);
}
}
_primeCache = new Tuple <long, IEnumerable <long> >(to, primes);
return(primes);
}
