/// <summary>
/// 主键权重随机
/// </summary>
public static string MTRandomKey(List <KeyValuePair <string, int> > weights, MersenneTwisterRandom mtRandom)
{
List <string> resultKeys = MTRandomKey(weights, 1, mtRandom);
if (resultKeys.Count() > 0)
{
return(resultKeys[0]);
}
return(null);
}
/// <summary>
/// 索引权重随机
/// </summary>
public static int MTRandomIndex(List <int> weights, MersenneTwisterRandom mtRandom)
{
List <int> resultIndexes = MTRandomIndex(weights, 1, mtRandom);
if (resultIndexes.Count() > 0)
{
return(resultIndexes[0]);
}
return(-1);
}
/// <summary>
/// 索引权重随机
/// </summary>
public static List <int> MTRandomIndex(List <int> weights, int count, MersenneTwisterRandom mtRandom)
{
int weightCount = weights.Count();
if (weightCount == 0 || count <= 0)
{
return(null);
}
int totalWeight = 0;
for (int i = 0; i < weightCount; i++)
{
totalWeight += weights[i];
}
if (totalWeight <= 0)
{
return(null);
}
List <int> resultIndexes = new List <int>(count);
HashSet <int> resultTags = new HashSet <int>();
while (resultIndexes.Count < count)
{
int randomWeight = mtRandom.Next(0, totalWeight);
int currentWeight = 0;
for (int i = 0; i < weightCount; i++)
{
currentWeight += weights[i];
if (currentWeight > randomWeight)
{
if (!resultTags.Contains(i))
{
resultIndexes.Add(i);
resultTags.Add(i);
}
break;
}
}
}
return(resultIndexes);
}
/// <summary>
/// 随机从 [0,max) 中取出不重复的 num 个整数
/// </summary>
public static int[] MTRandomNumbers(int num, int max, MersenneTwisterRandom mtRandom)
{
if (num < 0 || max < 0 || num > max)
{
return(null);
}
int[] result = new int[num];
int[] seed = new int[max];
for (int i = 0; i < max; i++)
{
seed[i] = i;
}
for (int i = 0; i < num; i++)
{
int index = mtRandom.Next(0, max - i);
result[i] = seed[index];
seed[index] = seed[num - i - 1];
}
return(result);
}
public WeightRandomGenerator(MersenneTwisterRandom mtRandom)
{
this.mtRandom = mtRandom;
}
public static int MTRandom(int min, int max, MersenneTwisterRandom mtRandom)
{
return(mtRandom.Next(min, max));
}
/// <summary>
/// 主键权重随机
/// </summary>
public static List <string> MTRandomKey(List <KeyValuePair <string, int> > weights, int count, MersenneTwisterRandom mtRandom)
{
int weightCount = weights.Count();
if (weightCount == 0 || count <= 0)
{
return(null);
}
List <int> weightValues = new List <int>(weightCount);
for (int i = 0; i < weightCount; i++)
{
weightValues.Add(weights[i].Value);
}
List <int> resultIndexes = MTRandomIndex(weightValues, count, mtRandom);
if (resultIndexes.Count() != count)
{
return(null);
}
List <string> resultKeys = new List <string>(count);
for (int i = 0; i < count; i++)
{
resultKeys.Add(weights[resultIndexes[i]].Key);
}
return(resultKeys);
}