/**
* Allocate a new instance of RandomProjection.
* @param {int} n - Original dimension.
* @param {int} t - Target/Projected dimension.
* @param {int} randomseed - Random seed.
*/
func New(n, t int, randomseed int64) *RandomProjection {
rando := rand.New(rand.NewSource(randomseed))
M, P := make([][]int, t), make([][]int, t)
rM, rP := 0, 0
probability := n / 6
var i uint = 0
parallel.For(i, uint(t), 1, func(i uint) {
orderedM, orderedP := make([]int, probability), make([]int, probability)
for j := 0; j < n; j++ {
rM, rP = rando.Intn(6), rando.Intn(6)
if rM == 0 {
orderedM = append(orderedM, j)
} else if rP == 0 {
orderedP = append(orderedP, j)
}
}
tmpM, tmpP := make([]int, len(orderedM)), make([]int, len(orderedP))
for k, val := range orderedM {
tmpM[k] = val
}
for k, val := range orderedP {
tmpP[k] = val
}
M[i], P[i] = tmpM, tmpP
})
return &RandomProjection{
M: M,
P: P,
n: n,
t: t,
random: rando,
}
}
/**
* Project onto a random matrix of {-1, 1} to produce a reduced dimensional vector.
* @param {[]float64} v - The input vector with the dimension t.
* @return {[]float64} - Returns a reduced dimensional vector.
*/
func (this *RandomProjection) Project(v []float64) []float64 {
var sum float64
r := make([]float64, this.t)
scale := math.Sqrt(3.0 / float64(this.t))
var i uint = 0
parallel.For(i, uint(this.t), 1, func(i uint) {
sum = 0.0
for _, val := range this.M[i] {
sum -= v[val] * scale
}
for _, val := range this.P[i] {
sum += v[val] * scale
}
r[i] = sum
})
return r
}
