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Updated index.rst
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# Copyright (c) 2012, GPy authors (see AUTHORS.txt).
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# Licensed under the BSD 3-clause license (see LICENSE.txt)
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from kernpart import kernpart
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import numpy as np
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import hashlib
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class rbf_testing(kernpart):
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"""
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Radial Basis Function kernel, aka squared-exponential, exponentiated quadratic or Gaussian kernel.
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.. math::
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k(r) = \sigma^2 \exp(- \frac{r^2}{2\ell}) \qquad \qquad \\text{ where } r = \sqrt{\frac{\sum_{i=1}^d (x_i-x^\prime_i)^2}{\ell^2}}
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where \ell is the lengthscale, \alpha the smoothness, \sigma^2 the variance and d the dimensionality of the input.
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:param D: the number of input dimensions
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:type D: int
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:param variance: the variance of the kernel
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:type variance: float
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:param lengthscale: the lengthscale of the kernel
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:type lengthscale: float
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.. Note: for rbf_testing with different lengthscale on each dimension, see rbf_testing_ARD
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"""
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def __init__(self,D,variance=1.,lengthscale=1.):
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self.D = D
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self.Nparam = 2
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self.name = 'rbf_testing'
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self._set_params(np.hstack((variance,lengthscale)))
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#initialize cache
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self._Z, self._mu, self._S = np.empty(shape=(3,1))
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self._X, self._X2, self._params = np.empty(shape=(3,1))
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def _get_params(self):
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return np.hstack((self.variance,self.lengthscale))
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def _set_params(self,x):
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self.variance, self.lengthscale = x
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self.lengthscale2 = np.square(self.lengthscale)
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#reset cached results
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self._X, self._X2, self._params = np.empty(shape=(3,1))
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self._Z, self._mu, self._S = np.empty(shape=(3,1)) # cached versions of Z,mu,S
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def _get_param_names(self):
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return ['variance','lengthscale']
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def K(self,X,X2,target):
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if X2 is None:
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X2 = X
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self._K_computations(X,X2)
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np.add(self.variance*self._K_dvar, target,target)
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def Kdiag(self,X,target):
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np.add(target,self.variance,target)
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def dK_dtheta(self,partial,X,X2,target):
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self._K_computations(X,X2)
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target[0] += np.sum(self._K_dvar*partial)
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target[1] += np.sum(self._K_dvar*self.variance*self._K_dist2/self.lengthscale*partial)
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def dKdiag_dtheta(self,partial,X,target):
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#NB: derivative of diagonal elements wrt lengthscale is 0
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target[0] += np.sum(partial)
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def dK_dX(self,partial,X,X2,target):
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self._K_computations(X,X2)
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_K_dist = X[:,None,:]-X2[None,:,:]
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dK_dX = np.transpose(-self.variance*self._K_dvar[:,:,np.newaxis]*_K_dist/self.lengthscale2,(1,0,2))
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target += np.sum(dK_dX*partial.T[:,:,None],0)
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def dKdiag_dX(self,partial,X,target):
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pass
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def _K_computations(self,X,X2):
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if not (np.all(X==self._X) and np.all(X2==self._X2)):
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self._X = X
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self._X2 = X2
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if X2 is None: X2 = X
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XXT = np.dot(X,X2.T)
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if X is X2:
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self._K_dist2 = (-2.*XXT + np.diag(XXT)[:,np.newaxis] + np.diag(XXT)[np.newaxis,:])/self.lengthscale2
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else:
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self._K_dist2 = (-2.*XXT + np.sum(np.square(X),1)[:,None] + np.sum(np.square(X2),1)[None,:])/self.lengthscale2
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# TODO Remove comments if this is fine.
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# Commented out by Neil as doesn't seem to be used elsewhere.
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#self._K_exponent = -0.5*self._K_dist2
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self._K_dvar = np.exp(-0.5*self._K_dist2)
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def psi0(self,Z,mu,S,target):
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target += self.variance
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def dpsi0_dtheta(self,partial,Z,mu,S,target):
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target[0] += 1.
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def dpsi0_dmuS(self,Z,mu,S,target_mu,target_S):
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pass
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def psi1(self,Z,mu,S,target):
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self._psi_computations(Z,mu,S)
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target += self._psi1
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def dpsi1_dtheta(self,partial,Z,mu,S,target):
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self._psi_computations(Z,mu,S)
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denom_deriv = S[:,None,:]/(self.lengthscale**3+self.lengthscale*S[:,None,:])
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d_length = self._psi1[:,:,None]*(self.lengthscale*np.square(self._psi1_dist/(self.lengthscale2+S[:,None,:])) + denom_deriv)
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target[0] += np.sum(partial*self._psi1/self.variance)
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target[1] += np.sum(d_length*partial[:,:,None])
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def dpsi1_dZ(self,partial,Z,mu,S,target):
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self._psi_computations(Z,mu,S)
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target += np.sum(partial[:,:,None]*-self._psi1[:,:,None]*self._psi1_dist/self.lengthscale2/self._psi1_denom,0)
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def dpsi1_dmuS(self,partial,Z,mu,S,target_mu,target_S):
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self._psi_computations(Z,mu,S)
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tmp = self._psi1[:,:,None]/self.lengthscale2/self._psi1_denom
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target_mu += np.sum(partial*tmp*self._psi1_dist,1)
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target_S += np.sum(partial*0.5*tmp*(self._psi1_dist_sq-1),1)
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def psi2(self,Z,mu,S,target):
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self._psi_computations(Z,mu,S)
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target += self._psi2.sum(0) #TODO: psi2 should be NxMxM (for het. noise)
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def dpsi2_dtheta(self,partial,Z,mu,S,target):
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"""Shape N,M,M,Ntheta"""
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self._psi_computations(Z,mu,S)
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d_var = np.sum(2.*self._psi2/self.variance,0)
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d_length = self._psi2[:,:,:,None]*(0.5*self._psi2_Zdist_sq*self._psi2_denom + 2.*self._psi2_mudist_sq + 2.*S[:,None,None,:]/self.lengthscale2)/(self.lengthscale*self._psi2_denom)
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d_length = d_length.sum(0)
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target[0] += np.sum(partial*d_var)
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target[1] += np.sum(d_length*partial)
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def dpsi2_dZ(self,partial,Z,mu,S,target):
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"""Returns shape N,M,M,Q"""
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self._psi_computations(Z,mu,S)
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dZ = self._psi2[:,:,:,None]/self.lengthscale2*(-0.5*self._psi2_Zdist + self._psi2_mudist/self._psi2_denom)
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target += np.sum(partial[None,:,:,None]*dZ,0).sum(1)
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def dpsi2_dmuS(self,Z,mu,S,target_mu,target_S):
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"""Think N,M,M,Q """
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self._psi_computations(Z,mu,S)
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tmp = self._psi2[:,:,:,None]/self.lengthscale2/self._psi2_denom
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target_mu += (partial*-tmp*2.*self._psi2_mudist).sum(1).sum(1)
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target_S += (partial*tmp*(2.*self._psi2_mudist_sq-1)).sum(1).sum(1)
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def _psi_computations(self,Z,mu,S):
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#here are the "statistics" for psi1 and psi2
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if not np.all(Z==self._Z):
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#Z has changed, compute Z specific stuff
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self._psi2_Zhat = 0.5*(Z[:,None,:] +Z[None,:,:]) # M,M,Q
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self._psi2_Zdist = Z[:,None,:]-Z[None,:,:] # M,M,Q
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self._psi2_Zdist_sq = np.square(self._psi2_Zdist)/self.lengthscale2 # M,M,Q
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self._Z = Z
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if not (np.all(Z==self._Z) and np.all(mu==self._mu) and np.all(S==self._S)):
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#something's changed. recompute EVERYTHING
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#TODO: make more efficient for large Q (using NDL's dot product trick)
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#psi1
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self._psi1_denom = S[:,None,:]/self.lengthscale2 + 1.
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self._psi1_dist = Z[None,:,:]-mu[:,None,:]
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self._psi1_dist_sq = np.square(self._psi1_dist)/self.lengthscale2/self._psi1_denom
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self._psi1_exponent = -0.5*np.sum(self._psi1_dist_sq+np.log(self._psi1_denom),-1)
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self._psi1 = self.variance*np.exp(self._psi1_exponent)
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#psi2
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self._psi2_denom = 2.*S[:,None,None,:]/self.lengthscale2+1. # N,M,M,Q
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self._psi2_mudist = mu[:,None,None,:]-self._psi2_Zhat #N,M,M,Q
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self._psi2_mudist_sq = np.square(self._psi2_mudist)/(self.lengthscale2*self._psi2_denom)
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self._psi2_exponent = np.sum(-self._psi2_Zdist_sq/4. -self._psi2_mudist_sq -0.5*np.log(self._psi2_denom),-1) #N,M,M
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self._psi2 = np.square(self.variance)*np.exp(self._psi2_exponent) # N,M,M
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self._Z, self._mu, self._S = Z, mu,S
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@ -1,23 +1,17 @@
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.. GPy documentation master file, created by
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.. GPy documentation master file, created by
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sphinx-quickstart on Fri Jan 18 15:30:28 2013.
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sphinx-quickstart on Fri Jan 18 17:36:01 2013.
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You can adapt this file completely to your liking, but it should at least
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You can adapt this file completely to your liking, but it should at least
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contain the root `toctree` directive.
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contain the root `toctree` directive.
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Welcome to GPy's documentation!
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Welcome to GPy's documentation!
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===============================
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===============================
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Added old command again
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And another thing
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Now what if I add this other hting
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Just checking another thing
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Contents:
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Contents:
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.. toctree::
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.. toctree::
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:maxdepth: 4
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:maxdepth: 4
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GPy
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GPy
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setup
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Indices and tables
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Indices and tables
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