From 4d355d823ffe33023e8eb05df5d65f27d1742a6c Mon Sep 17 00:00:00 2001 From: Nicolo Fusi Date: Mon, 11 Mar 2013 10:45:24 +0000 Subject: [PATCH] removed log_likelihood_gradients_transformed, now everything is done in the objective functions --- GPy/core/model.py | 63 ++++++++++++++++++++++++----------------------- 1 file changed, 32 insertions(+), 31 deletions(-) diff --git a/GPy/core/model.py b/GPy/core/model.py index b6cedbaf..703e615d 100644 --- a/GPy/core/model.py +++ b/GPy/core/model.py @@ -121,9 +121,6 @@ class model(parameterised): else: raise AttributeError, "no parameter matches %s"%name - - - def log_prior(self): """evaluate the prior""" return np.sum([p.lnpdf(x) for p, x in zip(self.priors,self._get_params()) if p is not None]) @@ -135,12 +132,11 @@ class model(parameterised): [np.put(ret,i,p.lnpdf_grad(xx)) for i,(p,xx) in enumerate(zip(self.priors,x)) if not p is None] return ret - def _log_likelihood_gradients_transformed(self): + def _transform_gradients(self, g): """ - Use self.log_likelihood_gradients and self.prior_gradients to get the gradients of the model. - Adjust the gradient for constraints and ties, return. + Takes a list of gradients and return an array of transformed gradients (positive/negative/tied/and so on) """ - g = self._log_likelihood_gradients() + self._log_prior_gradients() + x = self._get_params() g[self.constrained_positive_indices] = g[self.constrained_positive_indices]*x[self.constrained_positive_indices] g[self.constrained_negative_indices] = g[self.constrained_negative_indices]*x[self.constrained_negative_indices] @@ -152,6 +148,7 @@ class model(parameterised): else: return g + def randomize(self): """ Randomize the model. @@ -241,6 +238,27 @@ class model(parameterised): print "Warning! constraining %s postive"%name + def objective_function(self, x): + """ + The objective function passed to the optimizer. It combines the likelihood and the priors. + """ + self._set_params_transformed(x) + return -self.log_likelihood() - self.log_prior() + + def objective_function_gradients(self, x): + """ + Gets the gradients from the likelihood and the priors. + """ + self._set_params_transformed(x) + LL_gradients = self._transform_gradients(self._log_likelihood_gradients()) + prior_gradients = self._transform_gradients(self._log_prior_gradients()) + return -LL_gradients - prior_gradients + + def objective_and_gradients(self, x): + obj_f = self.objective_function(x) + obj_grads = self.objective_function_gradients(x) + return obj_f, obj_grads + def optimize(self, optimizer=None, start=None, **kwargs): """ Optimize the model using self.log_likelihood and self.log_likelihood_gradient, as well as self.priors. @@ -254,22 +272,12 @@ class model(parameterised): if optimizer is None: optimizer = self.preferred_optimizer - def f(x): - self._set_params_transformed(x) - return -self.log_likelihood()-self.log_prior() - def fp(x): - self._set_params_transformed(x) - return -self._log_likelihood_gradients_transformed() - def f_fp(x): - self._set_params_transformed(x) - return -self.log_likelihood()-self.log_prior(),-self._log_likelihood_gradients_transformed() - if start == None: start = self._get_params_transformed() optimizer = optimization.get_optimizer(optimizer) opt = optimizer(start, model = self, **kwargs) - opt.run(f_fp=f_fp, f=f, fp=fp) + opt.run(f_fp=self.objective_and_gradients, f=self.objective_function, fp=self.objective_function_gradients) self.optimization_runs.append(opt) self._set_params_transformed(opt.x_opt) @@ -357,12 +365,9 @@ class model(parameterised): dx = step*np.sign(np.random.uniform(-1,1,x.size)) #evaulate around the point x - self._set_params_transformed(x+dx) - f1,g1 = self.log_likelihood() + self.log_prior(), self._log_likelihood_gradients_transformed() - self._set_params_transformed(x-dx) - f2,g2 = self.log_likelihood() + self.log_prior(), self._log_likelihood_gradients_transformed() - self._set_params_transformed(x) - gradient = self._log_likelihood_gradients_transformed() + f1, g1 = self.objective_and_gradients(x+dx) + f2, g2 = self.objective_and_gradients(x-dx) + gradient = self.objective_function_gradients(x) numerical_gradient = (f1-f2)/(2*dx) global_ratio = (f1-f2)/(2*np.dot(dx,gradient)) @@ -398,14 +403,10 @@ class model(parameterised): for i in param_list: xx = x.copy() xx[i] += step - self._set_params_transformed(xx) - f1,g1 = self.log_likelihood() + self.log_prior(), self._log_likelihood_gradients_transformed()[i] + f1, g1 = self.objective_and_gradients(xx) xx[i] -= 2.*step - self._set_params_transformed(xx) - f2,g2 = self.log_likelihood() + self.log_prior(), self._log_likelihood_gradients_transformed()[i] - self._set_params_transformed(x) - gradient = self._log_likelihood_gradients_transformed()[i] - + f2, g2 = self.objective_and_gradients(xx) + gradient = self.objective_function_gradients(x)[i] numerical_gradient = (f1-f2)/(2*step) ratio = (f1-f2)/(2*step*gradient)