func pointFromDirec(from *optim.Point, direc []int, m optim.Mesh) *optim.Point {
pos := make([]float64, from.Len())
step := m.Step()
for i, x0 := range from.Pos {
pos[i] = x0 + float64(direc[i])*step
}
return &optim.Point{m.Nearest(pos), math.Inf(1)}
}
func (m *Method) Iterate(obj optim.Objectiver, mesh optim.Mesh) (best *optim.Point, neval int, err error) {
defer func() { m.iter++ }()
// project positions onto mesh
pmap := make(map[*optim.Point]*Particle, len(m.Pop))
points := make([]*optim.Point, len(m.Pop))
for i, particle := range m.Pop {
p := particle.Point.Clone()
p.Val = math.Inf(1)
points[i] = p
pmap[p] = particle
}
if mesh != nil {
for _, p := range points {
p.Pos = mesh.Nearest(p.Pos)
}
}
// evaluate current positions
results, n, err := m.Evaler.Eval(obj, points...)
if err != nil {
return &optim.Point{Val: math.Inf(1)}, n, err
}
for _, p := range results {
pmap[p].Update(p)
}
m.updateDb(mesh)
// TODO: write test to make sure this checks pbest.Best.Val instead of p.Val.
pbest := m.Pop.Best()
if pbest != nil && pbest.Best.Val < m.best.Val {
m.best = pbest.Best
}
// move particles and update current best
for _, p := range m.Pop {
p.Move(m.best, m.Vmax, m.InertiaFn(m.iter), m.Social, m.Cognition)
}
// Kill slow particles near global optimum.
// This MUST go after the updating of the iterator's best position.
for i, p := range m.Pop {
if p.Kill(m.best, m.Xtol, m.Vtol) {
m.Pop = append(m.Pop[:i], m.Pop[i+1:]...)
}
}
return m.best, n, nil
}
// Poll polls on mesh m centered on point from. It is responsible for
// selecting points and evaluating them with ev using obj. If a better
// point was found, it returns success == true, the point, and number of
// evaluations. If a better point was not found, it returns false, the
// from point, and the number of evaluations. If err is non-nil, success
// must be false and best must be from - neval may be non-zero.
func (cp *Poller) Poll(obj optim.Objectiver, ev optim.Evaler, m optim.Mesh, from *optim.Point) (success bool, best *optim.Point, neval int, err error) {
best = from
if cp.Spanner == nil {
cp.Spanner = Compass2N{}
}
pollpoints := []*optim.Point{}
// Only poll compass directions if we haven't polled from this point
// before. DONT DELETE - this can fire sometimes if the mesh isn't
// allowed to contract below a certain step (i.e. integer meshes).
h := from.Hash()
if h != cp.prevhash || cp.prevstep != m.Step() {
// TODO: write test that checks we poll compass dirs again if only mesh
// step changed (and not from point)
pollpoints = genPollPoints(from, cp.Spanner, m)
cp.prevhash = h
} else {
// Use random directions instead.
n := len(genPollPoints(from, cp.Spanner, m))
pollpoints = genPollPoints(from, &RandomN{N: n}, m)
}
cp.prevstep = m.Step()
// Add successful directions from last poll. We want to add these points
// in front of the other points so we can potentially stop earlier if
// polling opportunistically.
perms := optim.Rand.Perm(len(pollpoints))
// this is an extra safety check to make sure we don't index out of bounds
// on the perms slice
max := len(cp.keepdirecs)
if max > len(perms) {
max = len(perms)
}
for i, dir := range cp.keepdirecs[:max] {
swapindex := perms[i]
pollpoints[swapindex] = pointFromDirec(from, dir.dir, m)
}
// project points onto feasible region and mesh grid
if m != nil {
for _, p := range pollpoints {
p.Pos = m.Nearest(p.Pos)
}
}
cp.points = make([]*optim.Point, 0, len(pollpoints))
if cp.SkipEps == 0 {
cp.points = pollpoints
} else {
for _, p := range pollpoints {
// It is possible that due to the mesh gridding, the poll point is
// outside of constraints or bounds and will be rounded back to the
// current point. Check for this and skip the poll point if this is
// the case.
dist := optim.L2Dist(from, p)
if dist > cp.SkipEps {
cp.points = append(cp.points, p)
}
}
}
objstop := &objStopper{Objectiver: obj, Best: from.Val}
results, n, err := ev.Eval(objstop, cp.points...)
if err != nil && err != FoundBetterErr {
return false, best, n, err
}
// this is separate from best to allow all points better than from to be
// added to keepdirecs before we update the best point.
nextbest := from
// Sort results and keep the best Nkeep as poll directions.
for _, p := range results {
if p.Val < best.Val {
cp.keepdirecs = append(cp.keepdirecs, direc{direcbetween(from, p, m), p.Val})
}
if p.Val < nextbest.Val {
nextbest = p
}
}
best = nextbest
nkeep := cp.Nkeep
if max := len(pollpoints) / 4; max < nkeep {
nkeep = max
}
sort.Sort(byval(cp.keepdirecs))
if len(cp.keepdirecs) > nkeep {
cp.keepdirecs = cp.keepdirecs[:nkeep]
}
if best.Val < from.Val {
return true, best, n, nil
} else {
return false, from, n, nil
}
}
func (m *Method) updateDb(mesh optim.Mesh) {
if m.Db == nil {
return
}
tx, err := m.Db.Begin()
if err != nil {
panic(err.Error())
}
defer tx.Commit()
s0, err := tx.Prepare("INSERT INTO " + TblParticles + " (particle,iter,val,posid,velid,vel) VALUES (?,?,?,?,?,?);")
if checkdberr(err) {
return
}
s0b, err := tx.Prepare("INSERT INTO " + TblParticlesMeshed + " (particle,iter,val,posid) VALUES (?,?,?,?);")
if checkdberr(err) {
return
}
s1, err := tx.Prepare("INSERT INTO " + TblParticlesBest + " (particle,iter,best,posid) VALUES (?,?,?,?);")
if checkdberr(err) {
return
}
pts := []*optim.Point{}
for _, p := range m.Pop {
vel := &optim.Point{Pos: p.Vel}
pts = append(pts, p.Point)
pts = append(pts, p.Best) // best might be a projected location and not present in normal eval points
pts = append(pts, vel)
_, err := s0.Exec(p.Id, m.iter, p.Val, p.HashSlice(), vel.HashSlice(), p.L2Vel())
if checkdberr(err) {
return
}
_, err = s1.Exec(p.Id, m.iter, p.Best.Val, p.Best.HashSlice())
if checkdberr(err) {
return
}
pp := &optim.Point{mesh.Nearest(p.Pos), p.Val}
_, err = s0b.Exec(p.Id, m.iter, p.Val, pp.HashSlice())
if checkdberr(err) {
return
}
}
s2, err := tx.Prepare("INSERT INTO " + TblBest + " (iter,val,posid) VALUES (?,?,?);")
glob := m.best
_, err = s2.Exec(m.iter, glob.Val, glob.HashSlice())
if checkdberr(err) {
return
}
pts = append(pts, glob)
err = optim.RecordPointPos(tx, pts...)
if checkdberr(err) {
return
}
}