unfinished work on ratinoal quadratic kern

GPy/kern/__init__.py

@@ -1,12 +1,11 @@
 from _src.rbf import RBF
-from _src.white import White
 from _src.kern import Kern
 from _src.linear import Linear
-from _src.bias import Bias
+from _src.static import Bias, White
 from _src.brownian import Brownian
-from _src.stationary import Exponential, Matern32, Matern52, ExpQuad
+from _src.stationary import Exponential, Matern32, Matern52, ExpQuad, RatQuad
+from _src.mlp import MLP
 #import coregionalize
-#import exponential
 #import eq_ode1
 #import finite_dimensional
 #import fixed
@@ -14,10 +13,6 @@ from _src.stationary import Exponential, Matern32, Matern52, ExpQuad
 #import hetero
 #import hierarchical
 #import independent_outputs
-#import linear
-#import Matern32
-#import Matern52
-#import mlp
 #import ODE_1
 #import periodic_exponential
 #import periodic_Matern32
@@ -31,4 +26,3 @@ from _src.stationary import Exponential, Matern32, Matern52, ExpQuad
 #import rbf_inv
 #import spline
 #import symmetric
-#import white

GPy/kern/_src/mlp.py

@@ -1,11 +1,13 @@
 # Copyright (c) 2013, GPy authors (see AUTHORS.txt).
 # Licensed under the BSD 3-clause license (see LICENSE.txt)
 
-from kernpart import Kernpart
+from kern import Kern
+from ...core.parameterization import Param
+from ...core.parameterization.transformations import Logexp
 import numpy as np
 four_over_tau = 2./np.pi
 
-class MLP(Kernpart):
+class MLP(Kern):
     """
 
     Multi layer perceptron kernel (also known as arc sine kernel or neural network kernel)
@@ -29,85 +31,58 @@ class MLP(Kernpart):
 
     """
 
-    def __init__(self, input_dim, variance=1., weight_variance=None, bias_variance=100., ARD=False):
+    def __init__(self, input_dim, variance=1., weight_variance=1., bias_variance=100., name='mlp'):
-        self.input_dim = input_dim
+        super(Linear, self).__init__(input_dim, name)
-        self.ARD = ARD
+        self.variance = Param('variance', variance, Logexp)
-        if not ARD:
+        self.weight_variance = Param('weight_variance', weight_variance, Logexp)
-            self.num_params=3
+        self.bias_variance = Param('bias_variance', bias_variance, Logexp)
-            if weight_variance is not None:
+        self.add_parameters(self.variance, self.weight_variance, self.bias_variance)
-                weight_variance = np.asarray(weight_variance)
-                assert weight_variance.size == 1, "Only one weight variance needed for non-ARD kernel"
-            else:
-                weight_variance = 100.*np.ones(1)
-        else:
-            self.num_params = self.input_dim + 2
-            if weight_variance is not None:
-                weight_variance = np.asarray(weight_variance)
-                assert weight_variance.size == self.input_dim, "bad number of weight variances"
-            else:
-                weight_variance = np.ones(self.input_dim)
-            raise NotImplementedError
 
-        self.name='mlp'
-        self._set_params(np.hstack((variance, weight_variance.flatten(), bias_variance)))
 
-    def _get_params(self):
+    def K(self, X, X2=None):
-        return np.hstack((self.variance, self.weight_variance.flatten(), self.bias_variance))
-
-    def _set_params(self, x):
-        assert x.size == (self.num_params)
-        self.variance = x[0]
-        self.weight_variance = x[1:-1]
-        self.weight_std = np.sqrt(self.weight_variance)
-        self.bias_variance = x[-1]
-
-    def _get_param_names(self):
-        if self.num_params == 3:
-            return ['variance', 'weight_variance', 'bias_variance']
-        else:
-            return ['variance'] + ['weight_variance_%i' % i for i in range(self.lengthscale.size)] + ['bias_variance']
-
-    def K(self, X, X2, target):
-        """Return covariance between X and X2."""
         self._K_computations(X, X2)
-        target += self.variance*self._K_dvar
+        return self.variance*self._K_dvar
 
-    def Kdiag(self, X, target):
+    def Kdiag(self, X):
         """Compute the diagonal of the covariance matrix for X."""
         self._K_diag_computations(X)
-        target+= self.variance*self._K_diag_dvar
+        return self.variance*self._K_diag_dvar
 
-    def _param_grad_helper(self, dL_dK, X, X2, target):
+    def update_gradients_full(self, dL_dK, X, X2=None):
         """Derivative of the covariance with respect to the parameters."""
         self._K_computations(X, X2)
-        denom3 = self._K_denom*self._K_denom*self._K_denom
+        self.variance.gradient = np.sum(self._K_dvar*dL_dK)
+
+        denom3 = self._K_denom**3
         base = four_over_tau*self.variance/np.sqrt(1-self._K_asin_arg*self._K_asin_arg)
         base_cov_grad = base*dL_dK
 
         if X2 is None:
             vec = np.diag(self._K_inner_prod)
-            target[1] += ((self._K_inner_prod/self._K_denom 
+            self.weight_variance.gradient = ((self._K_inner_prod/self._K_denom
                            -.5*self._K_numer/denom3
                            *(np.outer((self.weight_variance*vec+self.bias_variance+1.), vec)
                              +np.outer(vec,(self.weight_variance*vec+self.bias_variance+1.))))*base_cov_grad).sum()
-            target[2] += ((1./self._K_denom 
+            self.bias_variance.gradient = ((1./self._K_denom
                            -.5*self._K_numer/denom3
                            *((vec[None, :]+vec[:, None])*self.weight_variance
                            +2.*self.bias_variance + 2.))*base_cov_grad).sum()
         else:
             vec1 = (X*X).sum(1)
             vec2 = (X2*X2).sum(1)
-            target[1] += ((self._K_inner_prod/self._K_denom 
+            self.weight_variance.gradient = ((self._K_inner_prod/self._K_denom
                            -.5*self._K_numer/denom3
                            *(np.outer((self.weight_variance*vec1+self.bias_variance+1.), vec2) + np.outer(vec1, self.weight_variance*vec2 + self.bias_variance+1.)))*base_cov_grad).sum()
-            target[2] += ((1./self._K_denom 
+            self.bias_variance.gradient = ((1./self._K_denom
                            -.5*self._K_numer/denom3
                            *((vec1[:, None]+vec2[None, :])*self.weight_variance
                              + 2*self.bias_variance + 2.))*base_cov_grad).sum()
 
-        target[0] += np.sum(self._K_dvar*dL_dK)
+    def update_gradients_diag(self, X):
+        raise NotImplementedError, "TODO"
 
-    def gradients_X(self, dL_dK, X, X2, target):
+
+    def gradients_X(self, dL_dK, X, X2):
         """Derivative of the covariance matrix with respect to X"""
         self._K_computations(X, X2)
         arg = self._K_asin_arg
@@ -116,10 +91,10 @@ class MLP(Kernpart):
         denom3 = denom*denom*denom
         if X2 is not None:
             vec2 = (X2*X2).sum(1)*self.weight_variance+self.bias_variance + 1.
-            target += four_over_tau*self.weight_variance*self.variance*((X2[None, :, :]/denom[:, :, None] - vec2[None, :, None]*X[:, None, :]*(numer/denom3)[:, :, None])*(dL_dK/np.sqrt(1-arg*arg))[:, :, None]).sum(1)
+            return four_over_tau*self.weight_variance*self.variance*((X2[None, :, :]/denom[:, :, None] - vec2[None, :, None]*X[:, None, :]*(numer/denom3)[:, :, None])*(dL_dK/np.sqrt(1-arg*arg))[:, :, None]).sum(1)
         else:
             vec = (X*X).sum(1)*self.weight_variance+self.bias_variance + 1.
-            target += 2*four_over_tau*self.weight_variance*self.variance*((X[None, :, :]/denom[:, :, None] - vec[None, :, None]*X[:, None, :]*(numer/denom3)[:, :, None])*(dL_dK/np.sqrt(1-arg*arg))[:, :, None]).sum(1)
+            return 2*four_over_tau*self.weight_variance*self.variance*((X[None, :, :]/denom[:, :, None] - vec[None, :, None]*X[:, None, :]*(numer/denom3)[:, :, None])*(dL_dK/np.sqrt(1-arg*arg))[:, :, None]).sum(1)
 
     def dKdiag_dX(self, dL_dKdiag, X, target):
         """Gradient of diagonal of covariance with respect to X"""
@@ -127,35 +102,26 @@ class MLP(Kernpart):
         arg = self._K_diag_asin_arg
         denom = self._K_diag_denom
         numer = self._K_diag_numer
-        target += four_over_tau*2.*self.weight_variance*self.variance*X*(1/denom*(1 - arg)*dL_dKdiag/(np.sqrt(1-arg*arg)))[:, None] 
+        return four_over_tau*2.*self.weight_variance*self.variance*X*(1./denom*(1. - arg)*dL_dKdiag/(np.sqrt(1-arg*arg)))[:, None]
 
 
     def _K_computations(self, X, X2):
         """Pre-computations for the covariance matrix (used for computing the covariance and its gradients."""
-        if self.ARD:
-            pass
-        else:
         if X2 is None:
             self._K_inner_prod = np.dot(X,X.T)
-                self._K_numer = self._K_inner_prod*self.weight_variance+self.bias_variance
             vec = np.diag(self._K_numer) + 1.
             self._K_denom = np.sqrt(np.outer(vec,vec))
-                self._K_asin_arg = self._K_numer/self._K_denom
-                self._K_dvar = four_over_tau*np.arcsin(self._K_asin_arg)
         else:
             self._K_inner_prod = np.dot(X,X2.T)
-                self._K_numer = self._K_inner_prod*self.weight_variance + self.bias_variance
             vec1 = (X*X).sum(1)*self.weight_variance + self.bias_variance + 1.
             vec2 = (X2*X2).sum(1)*self.weight_variance + self.bias_variance + 1.
             self._K_denom = np.sqrt(np.outer(vec1,vec2))
+        self._K_numer = self._K_inner_prod*self.weight_variance + self.bias_variance
         self._K_asin_arg = self._K_numer/self._K_denom
         self._K_dvar = four_over_tau*np.arcsin(self._K_asin_arg)
 
     def _K_diag_computations(self, X):
         """Pre-computations concerning the diagonal terms (used for computation of diagonal and its gradients)."""
-        if self.ARD:
-            pass
-        else:
         self._K_diag_numer = (X*X).sum(1)*self.weight_variance + self.bias_variance
         self._K_diag_denom = self._K_diag_numer+1.
         self._K_diag_asin_arg = self._K_diag_numer/self._K_diag_denom

GPy/kern/_src/static.py

@@ -7,7 +7,62 @@ from ...core.parameterization import Param
 from ...core.parameterization.transformations import Logexp
 import numpy as np
 
-class Bias(Kern):
+class Static(Kern):
+    def gradients_X(self, dL_dK, X, X2, target):
+        return np.zeros(X.shape)
+
+    def gradients_X_diag(self, dL_dKdiag, X, target):
+        return np.zeros(X.shape)
+
+    def gradients_Z_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
+        return np.zeros(Z.shape)
+
+    def gradients_muS_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
+        return np.zeros(mu.shape), np.zeros(S.shape)
+
+    def psi0(self, Z, mu, S):
+        return self.Kdiag(mu)
+
+    def psi1(self, Z, mu, S, target):
+        return self.K(mu, Z)
+
+    def psi2(Z, mu, S):
+        K = self.K(mu, Z)
+        return K[:,:,None]*K[:,None,:] # NB. more efficient implementations on inherriting classes
+
+
+class White(Static):
+    def __init__(self, input_dim, variance=1., name='white'):
+        super(White, self).__init__(input_dim, name)
+        self.input_dim = input_dim
+        self.variance = Param('variance', variance, Logexp())
+        self.add_parameters(self.variance)
+
+    def K(self, X, X2=None):
+        if X2 is None:
+            return np.eye(X.shape[0])*self.variance
+        else:
+            return np.zeros((X.shape[0], X2.shape[0]))
+
+    def Kdiag(self, X):
+        ret = np.ones(X.shape[0])
+        ret[:] = self.variance
+        return ret
+
+    def psi2(self, Z, mu, S, target):
+        return np.zeros((mu.shape[0], Z.shape[0], Z.shape[0]), dtype=np.float64)
+
+    def update_gradients_full(self, dL_dK, X):
+        self.variance.gradient = np.trace(dL_dK)
+
+    def update_gradients_diag(self, dL_dKdiag, X):
+        self.variance.gradient = dL_dKdiag.sum()
+
+    def update_gradients_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
+        self.variance.gradient = np.trace(dL_dKmm) + dL_dpsi0.sum()
+
+
+class Bias(Static):
     def __init__(self, input_dim, variance=1., name=None):
         super(Bias, self).__init__(input_dim, name)
         self.variance = Param("variance", variance, Logexp())
@@ -30,23 +85,6 @@ class Bias(Kern):
     def update_gradients_diag(self, dL_dKdiag, X):
         self.variance.gradient = dL_dK.sum()
 
-    def gradients_X(self, dL_dK,X, X2, target):
-        return np.zeros(X.shape)
-
-    def gradients_X_diag(self,dL_dKdiag,X,target):
-        return np.zeros(X.shape)
-
-
-    #---------------------------------------#
-    #             PSI statistics            #
-    #---------------------------------------#
-
-    def psi0(self, Z, mu, S):
-        return self.Kdiag(mu)
-
-    def psi1(self, Z, mu, S, target):
-        return self.K(mu, S)
-
     def psi2(self, Z, mu, S, target):
         ret = np.empty((mu.shape[0], Z.shape[0], Z.shape[0]), dtype=np.float64)
         ret[:] = self.variance**2
@@ -55,8 +93,3 @@ class Bias(Kern):
     def update_gradients_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
         self.variance.gradient = dL_dKmm.sum() + dL_dpsi0.sum() + dL_dpsi1.sum() + 2.*self.variance*dL_dpsi2.sum()
 
-    def gradients_Z_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
-        return np.zeros(Z.shape)
-
-    def gradients_muS_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
-        return np.zeros(mu.shape), np.zeros(S.shape)

GPy/kern/_src/stationary.py

@@ -193,8 +193,6 @@ class Matern52(Stationary):
         return(1./self.variance* (G_coef*G + orig + orig2))
 
 
-
-
 class ExpQuad(Stationary):
     def __init__(self, input_dim, variance=1., lengthscale=None, ARD=False, name='ExpQuad'):
         super(ExpQuad, self).__init__(input_dim, variance, lengthscale, ARD, name)
@@ -207,5 +205,26 @@ class ExpQuad(Stationary):
         dist = self._scaled_dist(X, X2)
         return -dist*self.K(X, X2)
 
+class RatQuad(Stationary):
+    def __init__(self, input_dim, variance=1., lengthscale=None, power=2., ARD=False, name='ExpQuad'):
+        super(RatQuad, self).__init__(input_dim, variance, lengthscale, ARD, name)
+        self.power = Param('power', power, Logexp)
+        self.add_parameters(self.power)
+
+    def K(self, X, X2=None):
+        r = self._scaled_dist(X, X2)
+        return self.variance*(1. + r**2/2.)**(-self.power)
+
+    def dK_dr(self, X, X2):
+        r = self._scaled_dist(X, X2)
+        return -self.variance*self.power*r*(1. + r**2/2)**(-self.power - 1.)
+
+    def update_gradients_full(self, dL_dK, X, X2=None):
+        super(RatQuad, self).update_gradients_full(dL_dK, X, X2)
+        r = self._scaled_dist(X, X2)
+        r2 = r**2
+        dpow = -2.**self.power*(r2 + 2.)**(-self.power)*np.log(0.5*(r2+2.))
+        self.power.gradient = np.sum(dL_dK*dpow)
+
 
 

GPy/kern/_src/white.py

@@ -6,73 +6,3 @@ import numpy as np
 from ...core.parameterization import Param
 from ...core.parameterization.transformations import Logexp
 
-class White(Kern):
-    """
-    White noise kernel.
-
-    :param input_dim: the number of input dimensions
-    :type input_dim: int
-    :param variance:
-    :type variance: float
-    """
-    def __init__(self,input_dim,variance=1., name='white'):
-        super(White, self).__init__(input_dim, name)
-        self.input_dim = input_dim
-        self.variance = Param('variance', variance, Logexp())
-        self.add_parameters(self.variance)
-
-    def K(self, X, X2=None):
-        if X2 is None:
-            return np.eye(X.shape[0])*self.variance
-        else:
-            return np.zeros((X.shape[0], X2.shape[0]))
-
-    def Kdiag(self,X):
-        ret = np.ones(X.shape[0])
-        ret[:] = self.variance
-        return ret
-
-    def update_gradients_full(self, dL_dK, X):
-        self.variance.gradient = np.trace(dL_dK)
-
-    def update_gradients_sparse(self, dL_dKmm, dL_dKnm, dL_dKdiag, X, Z):
-        self.variance.gradient = np.trace(dL_dKmm) + np.sum(dL_dKdiag)
-
-    def update_gradients_variational(self, dL_dKmm, dL_dpsi0, dL_dpsi1, dL_dpsi2, mu, S, Z):
-        raise NotImplementedError
-
-    def gradients_X(self,dL_dK,X,X2):
-        return np.zeros_like(X)
-
-    def psi0(self,Z,mu,S,target):
-        pass # target += self.variance
-
-    def dpsi0_dtheta(self,dL_dpsi0,Z,mu,S,target):
-        pass # target += dL_dpsi0.sum()
-
-    def dpsi0_dmuS(self,dL_dpsi0,Z,mu,S,target_mu,target_S):
-        pass
-
-    def psi1(self,Z,mu,S,target):
-        pass
-
-    def dpsi1_dtheta(self,dL_dpsi1,Z,mu,S,target):
-        pass
-
-    def dpsi1_dZ(self,dL_dpsi1,Z,mu,S,target):
-        pass
-
-    def dpsi1_dmuS(self,dL_dpsi1,Z,mu,S,target_mu,target_S):
-        pass
-
-    def psi2(self,Z,mu,S,target):
-        pass
-
-    def dpsi2_dZ(self,dL_dpsi2,Z,mu,S,target):
-        pass
-
-    def dpsi2_dtheta(self,dL_dpsi2,Z,mu,S,target):
-        pass
-
-    def dpsi2_dmuS(self,dL_dpsi2,Z,mu,S,target_mu,target_S):
-        pass