// MeanBatch predicts the mean at the set of locations specified by x. Stores in-place into yPred
// If yPred is nil new memory is allocated.
func (g *GP) MeanBatch(yPred []float64, x mat64.Matrix) []float64 {
rx, cx := x.Dims()
if cx != g.inputDim {
panic(badInputLength)
}
if yPred == nil {
yPred = make([]float64, rx)
}
ry := len(yPred)
if rx != ry {
panic(badOutputLength)
}
nSamples, _ := g.inputs.Dims()
covariance := mat64.NewDense(nSamples, rx, nil)
row := make([]float64, g.inputDim)
for j := 0; j < rx; j++ {
for k := 0; k < g.inputDim; k++ {
row[k] = x.At(j, k)
}
for i := 0; i < nSamples; i++ {
v := g.kernel.Distance(g.inputs.RawRowView(i), row)
covariance.Set(i, j, v)
}
}
yPredVec := mat64.NewVector(len(yPred), yPred)
yPredVec.MulVec(covariance.T(), g.sigInvY)
// Rescale the outputs
for i, v := range yPred {
yPred[i] = v*g.std + g.mean
}
return yPred
}
func MatrixToImage(src mat64.Matrix) image.Image {
width, height := src.Dims()
img := image.NewRGBA(image.Rect(0, 0, width, height))
for x := 0; x < width; x++ {
for y := 0; y < height; y++ {
img.Set(x, y, Float64ToColor(src.At(x, y)))
}
}
return img
}
func verifyInputs(initialBasic []int, c []float64, A mat64.Matrix, b []float64) error {
m, n := A.Dims()
if len(c) != n {
panic("lp: c vector incorrect length")
}
if len(b) != m {
panic("lp: b vector incorrect length")
}
if len(c) != n {
panic("lp: c vector incorrect length")
}
if len(initialBasic) != 0 && len(initialBasic) != m {
panic("lp: initialBasic incorrect length")
}
// Do some sanity checks so that ab does not become singular during the
// simplex solution. If the ZeroRow checks are removed then the code for
// finding a set of linearly indepent columns must be improved.
// Check that if a row of A only has zero elements that corresponding
// element in b is zero, otherwise the problem is infeasible.
// Otherwise return ErrZeroRow.
for i := 0; i < m; i++ {
isZero := true
for j := 0; j < n; j++ {
if A.At(i, j) != 0 {
isZero = false
break
}
}
if isZero && b[i] != 0 {
// Infeasible
return ErrInfeasible
} else if isZero {
return ErrZeroRow
}
}
// Check that if a column only has zero elements that the respective C vector
// is positive (otherwise unbounded). Otherwise return ErrZeroColumn.
for j := 0; j < n; j++ {
isZero := true
for i := 0; i < m; i++ {
if A.At(i, j) != 0 {
isZero = false
break
}
}
if isZero && c[j] < 0 {
return ErrUnbounded
} else if isZero {
return ErrZeroColumn
}
}
return nil
}
func CropMatrix(src mat64.Matrix, x0, y0, x1, y1 int) (*mat64.Dense, error) {
rows := y1 - y0 + 1
cols := x1 - x0 + 1
mtx := make([]float64, rows*cols)
for x := x0; x <= x1; x++ {
for y := y0; y <= y1; y++ {
mtx[(y-y0)*cols+(x-x0)] = src.At(x, y)
}
}
return mat64.NewDense(rows, cols, mtx), nil
}
func transpose(A mat64.Matrix) mat64.Matrix {
r, s := A.Dims()
var data []float64
for j := 0; j < s; j++ {
for i := 0; i < r; i++ {
data = append(data, A.At(i, j))
}
}
// Está medio chafa que regrese Dense, cómo hacemos para que regrese
// el mismo tipo de A?
return mat64.NewDense(s, r, data)
}
// PrintMat imprime una matriz con un formato entendible
func PrintMat(A mat64.Matrix) {
r, s := A.Dims()
fmt.Printf("(")
for i := 0; i < r; i++ {
fmt.Printf("\t")
for j := 0; j < s; j++ {
fmt.Printf("%0.1f\t", A.At(i, j))
}
if i != r-1 {
fmt.Printf("\n")
}
}
fmt.Printf(")\n")
}
// formKStar forms the covariance matrix between the inputs and new points.
func (g *GP) formKStar(x mat64.Matrix) *mat64.Dense {
// TODO(btracey): Parallelize
r, c := x.Dims()
n := len(g.outputs)
kStar := mat64.NewDense(n, r, nil)
data := make([]float64, c)
for j := 0; j < r; j++ {
for k := 0; k < c; k++ {
data[k] = x.At(j, k)
}
for i := 0; i < n; i++ {
row := g.inputs.RawRowView(i)
v := g.kernel.Distance(row, data)
kStar.Set(i, j, v)
}
}
return kStar
}
// StdDevBatch predicts the standard deviation at a set of locations of x.
func (g *GP) StdDevBatch(std []float64, x mat64.Matrix) []float64 {
r, c := x.Dims()
if c != g.inputDim {
panic(badInputLength)
}
if std == nil {
std = make([]float64, r)
}
if len(std) != r {
panic(badStorage)
}
// For a single point, the stddev is
// sigma = k(x,x) - k_*^T * K^-1 * k_*
// where k is the vector of kernels between the input points and the output points
// For many points, the formula is:
// nu_* = k(x_*, k_*) - k_*^T * K^-1 * k_*
// This creates the full covariance matrix which is an rxr matrix. However,
// the standard deviations are just the diagonal of this matrix. Instead, be
// smart about it and compute the diagonal terms one at a time.
kStar := g.formKStar(x)
var tmp mat64.Dense
tmp.SolveCholesky(g.cholK, kStar)
// set k(x_*, x_*) into std then subtract k_*^T K^-1 k_* , computed one row at a time
var tmp2 mat64.Vector
row := make([]float64, c)
for i := range std {
for k := 0; k < c; k++ {
row[k] = x.At(i, k)
}
std[i] = g.kernel.Distance(row, row)
tmp2.MulVec(kStar.ColView(i).T(), tmp.ColView(i))
rt, ct := tmp2.Dims()
if rt != 1 && ct != 1 {
panic("bad size")
}
std[i] -= tmp2.At(0, 0)
std[i] = math.Sqrt(std[i])
}
// Need to scale the standard deviation to be in the same units as y.
floats.Scale(g.std, std)
return std
}
//This is a temporal function. It returns the determinant of a 3x3 matrix. Panics if the matrix is not 3x3.
//It is also defined in the chem package which is not-so-clean.
func det(A mat64.Matrix) float64 {
r, c := A.Dims()
if r != 3 || c != 3 {
panic(ErrDeterminant)
}
return (A.At(0, 0)*(A.At(1, 1)*A.At(2, 2)-A.At(2, 1)*A.At(1, 2)) - A.At(1, 0)*(A.At(0, 1)*A.At(2, 2)-A.At(2, 1)*A.At(0, 2)) + A.At(2, 0)*(A.At(0, 1)*A.At(1, 2)-A.At(1, 1)*A.At(0, 2)))
}
