//To Do: store this matrix efficiently.
public unsafe void Refit(int[,] leafPreds)
{
Check.NonNull(leafPreds, nameof(leafPreds));
var len1 = leafPreds.GetLength(0);//nrow
var len2 = leafPreds.GetLength(1);//ncol
var data = new int[len1 * len2];
for (int i = 0; i< len1; ++i)
for(int j = 0; j < len2; ++j)
{
data[i * len2 + j] = leafPreds[i, j];
}
fixed (int *dataPtr = data)
PInvokeException.Check(PInvoke.BoosterRefit(Handle,dataPtr,len1,len2), nameof(PInvoke.BoosterRefit));
}
