Fixed quadrature for bernoulli likelihood, started adding Gaussian likelihood derivatives for quadrature

GPy/core/svgp.py

@@ -56,6 +56,7 @@ class SVGP(SparseGP):
             self.Z.gradient = self.kern.gradients_X(self.grad_dict['dL_dKmm'], self.Z) + self.kern.gradients_X(self.grad_dict['dL_dKmn'], self.Z, self.X)
 
 
+        self.likelihood.update_gradients(self.grad_dict['dL_dthetaL'])
         #update the variational parameter gradients:
         self.m.gradient = self.grad_dict['dL_dm']
         self.chol.gradient = self.grad_dict['dL_dchol']

GPy/inference/latent_function_inference/svgp.py

@@ -5,27 +5,9 @@ import numpy as np
 from posterior import Posterior
 
 class SVGP(LatentFunctionInference):
-    def likelihood_quadrature(self, Y, m, v):
-        Ysign = np.where(Y==1,1,-1).flatten()
-        from scipy import stats
-        self.gh_x, self.gh_w = np.polynomial.hermite.hermgauss(20)
-
-        #assume probit for now.
-        X = self.gh_x[None,:]*np.sqrt(2.*v[:,None]) + (m*Ysign)[:,None]
-        p = stats.norm.cdf(X)
-        p = np.clip(p, 1e-9, 1.-1e-9) # for numerical stability
-        N = stats.norm.pdf(X)
-        F = np.log(p).dot(self.gh_w)
-        NoverP = N/p
-        dF_dm = (NoverP*Ysign[:,None]).dot(self.gh_w)
-        dF_dv = -0.5*(NoverP**2 + NoverP*X).dot(self.gh_w)
-        return F, dF_dm, dF_dv
-
-
     def inference(self, q_u_mean, q_u_chol, kern, X, Z, likelihood, Y, Y_metadata=None):
         assert Y.shape[1]==1, "multi outputs not implemented"
 
-
         num_inducing = Z.shape[0]
         #expand cholesky representation
         L = choleskies.flat_to_triang(q_u_chol[:,None]).squeeze()
@@ -57,9 +39,7 @@ class SVGP(LatentFunctionInference):
         dKL_dKmm = 0.5*Kmmi - 0.5*Kmmi.dot(S).dot(Kmmi) - 0.5*Kmmim[:,None]*Kmmim[None,:]
 
         #quadrature for the likelihood
-        #F, dF_dmu, dF_dv = likelihood.variational_expectations(Y, mu, v)
+        F, dF_dmu, dF_dv, dF_dthetaL = likelihood.variational_expectations(Y, mu, v)
-        F, dF_dmu, dF_dv = self.likelihood_quadrature(Y, mu, v)
-
 
         #rescale the F term if working on a batch
         #F, dF_dmu, dF_dv =  F*batch_scale, dF_dmu*batch_scale, dF_dv*batch_scale
@@ -82,7 +62,7 @@ class SVGP(LatentFunctionInference):
         dL_dchol = 2.*np.dot(dL_dS, L)
         dL_dchol = choleskies.triang_to_flat(dL_dchol[:,:,None]).squeeze()
 
-        return Posterior(mean=q_u_mean, cov=S, K=Kmm), log_marginal, {'dL_dKmm':dL_dKmm, 'dL_dKmn':dL_dKmn, 'dL_dKdiag': dF_dv, 'dL_dm':dL_dm, 'dL_dchol':dL_dchol}
+        return Posterior(mean=q_u_mean, cov=S, K=Kmm), log_marginal, {'dL_dKmm':dL_dKmm, 'dL_dKmn':dL_dKmn, 'dL_dKdiag': dF_dv, 'dL_dm':dL_dm, 'dL_dchol':dL_dchol, 'dL_dthetaL':dF_dthetaL}
 
 
 

GPy/likelihoods/bernoulli.py

@@ -133,7 +133,7 @@ class Bernoulli(Likelihood):
         """
         #objective = y*np.log(inv_link_f) + (1.-y)*np.log(inv_link_f)
         p = np.where(y==1, inv_link_f, 1.-inv_link_f)
-        return np.log(np.clip(p, 1e-6 ,np.inf))
+        return np.log(np.clip(p, 1e-9 ,np.inf))
 
     def dlogpdf_dlink(self, inv_link_f, y, Y_metadata=None):
         """
@@ -152,7 +152,7 @@ class Bernoulli(Likelihood):
         """
         #grad = (y/inv_link_f) - (1.-y)/(1-inv_link_f)
         #grad = np.where(y, 1./inv_link_f, -1./(1-inv_link_f))
-        ff = np.clip(inv_link_f, 1e-6, 1-1e-6)
+        ff = np.clip(inv_link_f, 1e-9, 1-1e-9)
         denom = np.where(y, ff, -(1-ff))
         return 1./denom
 
@@ -180,7 +180,7 @@ class Bernoulli(Likelihood):
         #d2logpdf_dlink2 = -y/(inv_link_f**2) - (1-y)/((1-inv_link_f)**2)
         #d2logpdf_dlink2 = np.where(y, -1./np.square(inv_link_f), -1./np.square(1.-inv_link_f))
         arg = np.where(y, inv_link_f, 1.-inv_link_f)
-        ret =  -1./np.square(np.clip(arg, 1e-3, np.inf))
+        ret =  -1./np.square(np.clip(arg, 1e-9, 1e9))
         if np.any(np.isinf(ret)):
             stop
         return ret

GPy/likelihoods/gaussian.py

@@ -316,3 +316,11 @@ class Gaussian(Likelihood):
         v = var_star + self.variance
         return -0.5*np.log(2*np.pi) -0.5*np.log(v) - 0.5*np.square(y_test - mu_star)/v
 
+    def variational_expectations(self, Y, m, v, gh_points=None):
+        lik_var = float(self.variance)
+        F = -0.5*np.log(2*np.pi) -0.5*np.log(lik_var) - 0.5*(np.square(Y) + np.square(m) + v - 2*m.dot(Y))/lik_var
+        dF_dmu = (Y - m)/lik_var
+        dF_dv = -0.5/lik_var
+        dF_dlik_var = -0.5/lik_var + 0.5(np.square(Y) + np.square(m) + v - 2*m.dot(Y))/(lik_var**2)
+        dF_dtheta = [dF_dlik_var]
+        return F, dF_dmu, dF_dv, dF_dtheta

GPy/likelihoods/likelihood.py

@@ -133,7 +133,7 @@ class Likelihood(Parameterized):
 
     def variational_expectations(self, Y, m, v, gh_points=None):
         """
-        Use Gauss-Hermite Quadrature to compute 
+        Use Gauss-Hermite Quadrature to compute
 
            E_p(f) [ log p(y|f) ]
            d/dm E_p(f) [ log p(y|f) ]
@@ -143,9 +143,10 @@ class Likelihood(Parameterized):
 
         if no gh_points are passed, we construct them using defualt options
         """
+        #May be broken
 
         if gh_points is None:
-            gh_x, gh_w = np.polynomial.hermite.hermgauss(12)
+            gh_x, gh_w = np.polynomial.hermite.hermgauss(20)
         else:
             gh_x, gh_w = gh_points
 
@@ -156,15 +157,15 @@ class Likelihood(Parameterized):
         X = gh_x[None,:]*np.sqrt(2.*v[:,None]) + m[:,None]
 
         #evaluate the likelhood for the grid. First ax indexes the data (and mu, var) and the second indexes the grid.
-        # broadcast needs to be handled carefully. 
+        # broadcast needs to be handled carefully.
         logp = self.logpdf(X,Y[:,None])
         dlogp_dx = self.dlogpdf_df(X, Y[:,None])
         d2logp_dx2 = self.d2logpdf_df2(X, Y[:,None])
 
         #clipping for numerical stability
-        logp = np.clip(logp,-1e6,1e6)
+        #logp = np.clip(logp,-1e9,1e9)
-        dlogp_dx = np.clip(dlogp_dx,-1e6,1e6)
+        #dlogp_dx = np.clip(dlogp_dx,-1e9,1e9)
-        d2logp_dx2 = np.clip(d2logp_dx2,-1e6,1e6)
+        #d2logp_dx2 = np.clip(d2logp_dx2,-1e9,1e9)
 
         #average over the gird to get derivatives of the Gaussian's parameters
         F = np.dot(logp, gh_w)
@@ -176,10 +177,8 @@ class Likelihood(Parameterized):
         if np.any(np.isnan(dF_dm)) or np.any(np.isinf(dF_dm)):
             stop
 
-        return F.reshape(*shape), dF_dm.reshape(*shape), dF_dv.reshape(*shape)
+        dF_dtheta = None # Not yet implemented
-
+        return F.reshape(*shape), dF_dm.reshape(*shape), dF_dv.reshape(*shape), None
-
-
 
     def predictive_mean(self, mu, variance, Y_metadata=None):
         """