def testGDelta(self):
# usually, Gdelta==G
GP = GaussianProcess(GaussianKernel_iso([0.05]))
X = lhcSample([[0., 1.]], 5, seed=10)
Y = [x**2 for x in X]
GP.train(X, Y)
G = (Y[0] - max(Y)) / (Y[0] - 1)
self.failUnlessEqual(G, Gdelta(GP, [[0., 1.]], Y[0], 1.0, 0.01))
# sometimes, though, Gdelta > G -- this GP has a very high confidence
# prediction of a very good point at x ~ .65
GP = GaussianProcess(GaussianKernel_iso([0.1]))
X = array([[.5], [.51], [.59], [.6]])
Y = array([1., 2., 2., 1.])
GP.train(X, Y)
# figure(1)
# A = arange(0, 1, 0.01)
# post = [GP.posterior(x) for x in A]
# plot(A, [p[0] for p in post], 'k-')
# plot(A, [p[0]+p[1] for p in post], 'k:')
# show()
G = (Y[0] - max(Y)) / (Y[0] - 4.0)
Gd = Gdelta(GP, [[0., 1.]], Y[0], 4.0, 0.01)
self.failUnless(G < Gd)
# however, if there is more variance, we will collapse back to G
GP = GaussianProcess(GaussianKernel_iso([.001]))
GP.train(X, Y)
G = (Y[0] - max(Y)) / (Y[0] - 4.0)
self.failUnlessEqual(G, Gdelta(GP, [[0., 1.]], Y[0], 4.0, 0.01))
def testXi(self):
S5 = Shekel5()
GP1 = GaussianProcess(GaussianKernel_iso([.2]))
# self.failUnlessEqual(GP1.xi, 0.0)
X = lhcSample(S5.bounds, 10, seed=0)
Y = [S5.f(x) for x in X]
GP1.addData(X, Y)
eif1 = EI(GP1, xi=0.0)
dopt1, _ = direct(eif1.negf, S5.bounds, maxiter=10)
copt1, _ = cdirect(eif1.negf, S5.bounds, maxiter=10)
mopt1, _ = maximizeEI(GP1, S5.bounds, xi=0.0, maxiter=10)
self.failUnlessAlmostEqual(dopt1, copt1, 4)
self.failUnlessAlmostEqual(-dopt1, mopt1, 4)
self.failUnlessAlmostEqual(-copt1, mopt1, 4)
GP2 = GaussianProcess(GaussianKernel_iso([.3]), X, Y)
eif2 = EI(GP2, xi=0.01)
self.failUnlessEqual(eif2.xi, 0.01)
dopt2, _ = direct(eif2.negf, S5.bounds, maxiter=10)
copt2, _ = cdirect(eif2.negf, S5.bounds, maxiter=10)
mopt2, _ = maximizeEI(GP2, S5.bounds, xi=0.01, maxiter=10)
self.failUnlessAlmostEqual(dopt2, copt2, 4)
self.failUnlessAlmostEqual(-dopt2, mopt2, 4)
self.failUnlessAlmostEqual(-copt2, mopt2, 4)
self.failIfAlmostEqual(dopt1, dopt2, 4)
self.failIfAlmostEqual(copt1, copt2, 4)
self.failIfAlmostEqual(mopt1, mopt2, 4)
GP3 = GaussianProcess(GaussianKernel_iso([.3]), X, Y)
eif3 = EI(GP3, xi=0.1)
dopt3, _ = direct(eif3.negf, S5.bounds, maxiter=10)
copt3, _ = cdirect(eif3.negf, S5.bounds, maxiter=10)
mopt3, _ = maximizeEI(GP3, S5.bounds, xi=0.1, maxiter=10)
self.failUnlessAlmostEqual(dopt3, copt3, 4)
self.failUnlessAlmostEqual(-dopt3, mopt3, 4)
self.failUnlessAlmostEqual(-copt3, mopt3, 4)
self.failIfAlmostEqual(dopt1, dopt3, 4)
self.failIfAlmostEqual(copt1, copt3, 4)
self.failIfAlmostEqual(mopt1, mopt3, 4)
self.failIfAlmostEqual(dopt2, dopt3, 4)
self.failIfAlmostEqual(copt2, copt3, 4)
self.failIfAlmostEqual(mopt2, mopt3, 4)
def test2DcEI(self):
f = lambda x: sum(sin(x))
bounds = [[0., 5.], [0., 5.]]
X = lhcSample(bounds, 5, seed=23)
Y = [f(x) for x in X]
kernel = GaussianKernel_iso(array([1.0]))
GP = GaussianProcess(kernel, X, Y)
maxei = maximizeEI(GP, bounds)
if False:
figure(1)
c0 = [(i / 100.) * (bounds[0][1] - bounds[0][0]) + bounds[0][0]
for i in range(101)]
c1 = [(i / 100.) * (bounds[1][1] - bounds[1][0]) + bounds[1][0]
for i in range(101)]
z = array([[GP.ei(array([i, j])) for i in c0] for j in c1])
ax = plt.subplot(111)
ax.contour(c0, c1, z, 10, alpha=0.5, cmap=cm.Blues_r)
plot([x[0] for x in X], [x[1] for x in X], 'ro')
for i in range(len(X)):
annotate('%2f' % Y[i], X[i])
plot(maxei[1][0], maxei[1][1], 'ko')
show()
def test():
GP = GaussianProcess(GaussianKernel_iso([.2, 1.0]))
X = array([[.2], [.3], [.5], [1.5]])
Y = [1, 0, 1, .75]
GP.addData(X, Y)
figure(1)
A = arange(0, 2, 0.01)
mu = array([GP.mu(x) for x in A])
sig2 = array([GP.posterior(x)[1] for x in A])
Ei = EI(GP)
ei = [-Ei.negf(x) for x in A]
Pi = PI(GP)
pi = [-Pi.negf(x) for x in A]
Ucb = UCB(GP, 1, T=2)
ucb = [-Ucb.negf(x) for x in A]
ax = subplot(1, 1, 1)
ax.plot(A, mu, 'k-', lw=2)
xv, yv = poly_between(A, mu - sig2, mu + sig2)
ax.fill(xv, yv, color="#CCCCCC")
ax.plot(A, ei, 'g-', lw=2, label='EI')
ax.plot(A, ucb, 'g--', lw=2, label='UCB')
ax.plot(A, pi, 'g:', lw=2, label='PI')
ax.plot(X, Y, 'ro')
ax.legend()
draw()
show()
def testXi(self):
S5 = Shekel5()
GP1 = GaussianProcess(GaussianKernel_iso([.2]))
# self.failUnlessEqual(GP1.xi, 0.0)
X = lhcSample(S5.bounds, 10, seed=0)
Y = [S5.f(x) for x in X]
GP1.addData(X, Y)
ucbf1 = UCB(GP1, len(S5.bounds), scale=0.5)
dopt1, _ = direct(ucbf1.negf, S5.bounds, maxiter=10)
copt1, _ = cdirect(ucbf1.negf, S5.bounds, maxiter=10)
mopt1, _ = maximizeUCB(GP1, S5.bounds, scale=0.5, maxiter=10)
self.failUnlessAlmostEqual(dopt1, copt1, 4)
self.failUnlessAlmostEqual(-dopt1, mopt1, 4)
self.failUnlessAlmostEqual(-copt1, mopt1, 4)
GP2 = GaussianProcess(GaussianKernel_iso([.3]), X, Y)
ucbf2 = UCB(GP2, len(S5.bounds), scale=0.01)
dopt2, _ = direct(ucbf2.negf, S5.bounds, maxiter=10)
copt2, _ = cdirect(ucbf2.negf, S5.bounds, maxiter=10)
mopt2, _ = maximizeUCB(GP2, S5.bounds, scale=.01, maxiter=10)
self.failUnlessAlmostEqual(dopt2, copt2, 4)
self.failUnlessAlmostEqual(-dopt2, mopt2, 4)
self.failUnlessAlmostEqual(-copt2, mopt2, 4)
self.failIfAlmostEqual(dopt1, dopt2, 4)
self.failIfAlmostEqual(copt1, copt2, 4)
self.failIfAlmostEqual(mopt1, mopt2, 4)
GP3 = GaussianProcess(GaussianKernel_iso([.3]), X, Y)
ucbf3 = UCB(GP3, len(S5.bounds), scale=.9)
dopt3, _ = direct(ucbf3.negf, S5.bounds, maxiter=10)
copt3, _ = cdirect(ucbf3.negf, S5.bounds, maxiter=10)
mopt3, _ = maximizeUCB(GP3, S5.bounds, scale=0.9, maxiter=10)
self.failUnlessAlmostEqual(dopt3, copt3, 4)
self.failUnlessAlmostEqual(-dopt3, mopt3, 4)
self.failUnlessAlmostEqual(-copt3, mopt3, 4)
self.failIfAlmostEqual(dopt1, dopt3, 4)
self.failIfAlmostEqual(copt1, copt3, 4)
self.failIfAlmostEqual(mopt1, mopt3, 4)
self.failIfAlmostEqual(dopt2, dopt3, 4)
self.failIfAlmostEqual(copt2, copt3, 4)
self.failIfAlmostEqual(mopt2, mopt3, 4)
def _testKernelMaxEI(self):
# test different methods of optimizing kernel
S5 = Shekel5()
hv = 0.1
testkernels = [GaussianKernel_iso([hv]),
GaussianKernel_ard([hv, hv, hv, hv]),
MaternKernel3([hv, 1.0])]
# MaternKernel5([hv, 1.0])]
for kernel in testkernels:
# print
# print kernel.__class__
# train GPs
X = lhcSample(S5.bounds, 10, seed=0)
Y = [S5.f(x) for x in X]
GP = GaussianProcess(kernel, X, Y)
eif = EI(GP)
dopt, doptx = direct(eif.negf, S5.bounds, maxiter=10)
copt, coptx = cdirect(eif.negf, S5.bounds, maxiter=10)
mopt, moptx = maximizeEI(GP, S5.bounds, maxiter=10)
# print dopt, doptx
# print copt, coptx
# print mopt, moptx
self.failUnlessAlmostEqual(dopt, copt, 4)
self.failUnlessAlmostEqual(-dopt, mopt, 4)
self.failUnlessAlmostEqual(-copt, mopt, 4)
self.failUnless(sum(abs(doptx-coptx)) < .01)
self.failUnless(sum(abs(moptx-coptx)) < .01)
self.failUnless(sum(abs(moptx-doptx)) < .01)
# train GP w/prior
pX = lhcSample(S5.bounds, 100, seed=101)
pY = [S5.f(x) for x in pX]
prior = RBFNMeanPrior()
prior.train(pX, pY, bounds=S5.bounds, k=10, seed=102)
GP = GaussianProcess(kernel, X, Y, prior=prior)
eif = EI(GP)
pdopt, pdoptx = direct(eif.negf, S5.bounds, maxiter=10)
pcopt, pcoptx = cdirect(eif.negf, S5.bounds, maxiter=10)
pmopt, pmoptx = maximizeEI(GP, S5.bounds, maxiter=10)
self.failIfAlmostEqual(pdopt, dopt, 3)
self.failUnlessAlmostEqual(pdopt, pcopt, 4)
self.failUnlessAlmostEqual(-pdopt, pmopt, 4)
self.failUnlessAlmostEqual(-pcopt, pmopt, 4)
self.failUnless(sum(abs(pdoptx-pcoptx)) < .01)
self.failUnless(sum(abs(pmoptx-pcoptx)) < .01)
self.failUnless(sum(abs(pmoptx-pdoptx)) < .01)
def train(self,
X,
Y,
bounds=None,
k=10,
delta=100,
kernel=None,
seed=None):
"""
using the X, Y data, train a Radial Basis Function network as follows:
1. cluster the data into k clusters using k-means
2. using the centroids of each cluster as the origins of the RBFs,
learn the RBF weights beta
'RBF' is a radial basis function of the form y = rbf(r, args=rbfargs), where
r = ||c-x|| and 'args' is any necessary arguments for the RBF.
Returns the means and weights of the RNF network.
"""
def RBFN(means, x):
norms = [linalg.norm(m - x) for m in means]
rbf = array([self.RBF(n) for n in norms])
return rbf
rs = numpy.random.RandomState(seed)
# let's cluster the data using k means. first, project X to unit hypercube
if bounds is not None:
self.lowerb = array([b[0] for b in bounds])
self.width = array([b[1] - b[0] for b in bounds])
X = array([(x - self.lowerb) / self.width for x in X])
Y = array(Y)
NX, _ = X.shape
r = range(NX)
rs.shuffle(r)
means = X[r[:k]]
for _ in xrange(10):
# assign each cluster to closest mean
C = [argmin([linalg.norm(m - x) for m in means]) for x in X]
# means become centroids of their clusters
means = []
for j in xrange(k):
clust = [x for x, c in zip(X, C) if c == j]
if len(clust) == 0:
# for empty clusters, restart centered on a random datum
means.append(X[rs.randint(NX)])
else:
means.append(array(clust).mean(0))
# okay, now we can analytically compute RBF weights
if kernel is None:
kernel = GaussianKernel_iso(array([.2]))
reg = .1
# L = cholesky(kernel.covMatrix(X))
while True:
try:
invK = linalg.inv(matrix(kernel.covMatrix(X)) +
eye(NX) * reg) # add regularizer
except LinAlgError:
reg *= 2
print 'LinAlgError: increase regularizer to %f' % reg
else:
break
# compute unweighted basis values for the data
H = matrix([RBFN(means, x) for x in X])
Y = matrix(Y)
try:
beta = linalg.inv(H.T * invK * H + delta**-2) * (H.T * invK * Y.T)
except linalg.linalg.LinAlgError:
# add a powerful regularizer...
beta = linalg.inv(H.T * invK * H + eye(H.shape[1]) +
delta**-2) * (H.T * invK * Y.T)
## this is from Ruben's paper. I can't get it to make sense...
# a = b = 10.
# sighat = diag((b + Y*K.I*Y.T - (H.T*K.I*H + delta**-2) * (muhat*muhat.T)) / (NX+a+2))
# beta should be a 1D array
self.beta = array(beta).reshape(-1)
self.means = means