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no longer caching denom in psi2_rbf

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James Hensman 2014-02-28 12:59:49 +00:00
parent ba1d6697e5
commit ab7dff9a3d
1 changed files with 14 additions and 69 deletions
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83
GPy/kern/_src/rbf.py
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@ -48,7 +48,7 @@ class RBF(Stationary):
if isinstance(variational_posterior, variational.SpikeAndSlabPosterior):
psi2, _, _, _, _, _, _ = ssrbf_psi_comp._psi2computations(self.variance, self.lengthscale, Z, variational_posterior.mean, variational_posterior.variance, variational_posterior.binary_prob)
else:
_, _, _, _, _, psi2 = self._psi2computations(Z, variational_posterior)
_, _, _, _, psi2 = self._psi2computations(Z, variational_posterior)
return psi2
def update_gradients_expectations(self, dL_dpsi0, dL_dpsi1, dL_dpsi2, Z, variational_posterior):
@ -80,19 +80,16 @@ class RBF(Stationary):
denom, _, dist_sq, psi1 = self._psi1computations(Z, variational_posterior)
d_length = psi1[:,:,None] * ((dist_sq - 1.)/(self.lengthscale*denom) +1./self.lengthscale)
dpsi1_dlength = d_length * dL_dpsi1[:, :, None]
if not self.ARD:
self.lengthscale.gradient += dpsi1_dlength.sum()
else:
if self.ARD:
self.lengthscale.gradient += dpsi1_dlength.sum(0).sum(0)
else:
self.lengthscale.gradient += dpsi1_dlength.sum()
self.variance.gradient += np.sum(dL_dpsi1 * psi1) / self.variance
#from psi2
S = variational_posterior.variance
denom, _, Zdist_sq, _, mudist_sq, psi2 = self._psi2computations(Z, variational_posterior)
d_length = 2.*psi2[:, :, :, None] * (Zdist_sq * denom + mudist_sq + S[:, None, None, :] / l2) / (self.lengthscale * denom)
#TODO: combine denom and l2 as denom_l2??
#TODO: tidy the above!
#TODO: tensordot below?
_, Zdist_sq, _, mudist_sq, psi2 = self._psi2computations(Z, variational_posterior)
d_length = 2.*psi2[:, :, :, None] * (Zdist_sq * (2.*S[:,None,None,:]/l2 + 1.) + mudist_sq + S[:, None, None, :] / l2) / (2.*S[:,None,None,:] + l2)*self.lengthscale
dpsi2_dlength = d_length * dL_dpsi2[:, :, :, None]
if not self.ARD:
@ -125,9 +122,11 @@ class RBF(Stationary):
grad = np.sum(dL_dpsi1[:, :, None] * dpsi1_dZ, 0)
#psi2
denom, Zdist, Zdist_sq, mudist, mudist_sq, psi2 = self._psi2computations(Z, variational_posterior)
Zdist, Zdist_sq, mudist, mudist_sq, psi2 = self._psi2computations(Z, variational_posterior)
term1 = Zdist / l2 # M, M, Q
term2 = mudist / denom / l2 # N, M, M, Q
S = variational_posterior.variance
term2 = mudist / (2.*S[:,None,None,:] + l2) # N, M, M, Q
dZ = psi2[:, :, :, None] * (term1[None, :, :, :] + term2) #N,M,M,Q
grad += 2*(dL_dpsi2[:, :, :, None] * dZ).sum(0).sum(0)
@ -159,8 +158,9 @@ class RBF(Stationary):
grad_mu = np.sum(dL_dpsi1[:, :, None] * tmp * dist, 1)
grad_S = np.sum(dL_dpsi1[:, :, None] * 0.5 * tmp * (dist_sq - 1), 1)
#psi2
denom, _, _, mudist, mudist_sq, psi2 = self._psi2computations(Z, variational_posterior)
tmp = psi2[:, :, :, None] / l2 / denom
_, _, mudist, mudist_sq, psi2 = self._psi2computations(Z, variational_posterior)
S = variational_posterior.variance
tmp = psi2[:, :, :, None] / (2.*S[:,None,None,:] + l2)
grad_mu += -2.*(dL_dpsi2[:, :, :, None] * tmp * mudist).sum(1).sum(1)
grad_S += (dL_dpsi2[:, :, :, None] * tmp * (2.*mudist_sq - 1)).sum(1).sum(1)
@ -170,61 +170,6 @@ class RBF(Stationary):
# Precomputations #
#---------------------------------------#
#TODO: this function is unused, but it will be useful in the stationary class
def _dL_dlengthscales_via_K(self, dL_dK, X, X2):
"""
A helper function for update_gradients_* methods
Computes the derivative of the objective L wrt the lengthscales via
dL_dl = sum_{i,j}(dL_dK_{ij} dK_dl)
assumes self._K_computations has just been called.
This is only valid if self.ARD=True
"""
target = np.zeros(self.input_dim)
dvardLdK = self._K_dvar * dL_dK
var_len3 = self.variance / np.power(self.lengthscale, 3)
if X2 is None:
# save computation for the symmetrical case
dvardLdK = dvardLdK + dvardLdK.T
code = """
int q,i,j;
double tmp;
for(q=0; q<input_dim; q++){
tmp = 0;
for(i=0; i<num_data; i++){
for(j=0; j<i; j++){
tmp += (X(i,q)-X(j,q))*(X(i,q)-X(j,q))*dvardLdK(i,j);
}
}
target(q) += var_len3(q)*tmp;
}
"""
num_data, num_inducing, input_dim = X.shape[0], X.shape[0], self.input_dim
X, dvardLdK, var_len3 = param_to_array(X, dvardLdK, var_len3)
weave.inline(code, arg_names=['num_data', 'num_inducing', 'input_dim', 'X', 'target', 'dvardLdK', 'var_len3'], type_converters=weave.converters.blitz, **self.weave_options)
else:
code = """
int q,i,j;
double tmp;
for(q=0; q<input_dim; q++){
tmp = 0;
for(i=0; i<num_data; i++){
for(j=0; j<num_inducing; j++){
tmp += (X(i,q)-X2(j,q))*(X(i,q)-X2(j,q))*dvardLdK(i,j);
}
}
target(q) += var_len3(q)*tmp;
}
"""
num_data, num_inducing, input_dim = X.shape[0], X2.shape[0], self.input_dim
X, X2, dvardLdK, var_len3 = param_to_array(X, X2, dvardLdK, var_len3)
weave.inline(code, arg_names=['num_data', 'num_inducing', 'input_dim', 'X', 'X2', 'target', 'dvardLdK', 'var_len3'], type_converters=weave.converters.blitz, **self.weave_options)
return target
@Cache_this(limit=1)
def _psi1computations(self, Z, vp):
mu, S = vp.mean, vp.variance
@ -309,4 +254,4 @@ class RBF(Stationary):
arg_names=['N', 'M', 'Q', 'mu', 'Zhat', 'mudist_sq', 'mudist', 'denom_l2', 'Zdist_sq', 'half_log_denom', 'psi2', 'variance_sq'],
type_converters=weave.converters.blitz, **self.weave_options)
return denom, Zdist, Zdist_sq, mudist, mudist_sq, psi2
return Zdist, Zdist_sq, mudist, mudist_sq, psi2