def __call__(self, x, observed = True, regularize=True, Uo_Cxo=None):
# Record original shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape)>1:
orig_shape = orig_shape[:-1]
if regularize:
x=regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
# Safety.
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x does not match the number of spatial dimensions of the Mean instance's base mesh."
# Evaluate the unobserved mean
M = self.eval_fun(x,**self.params).squeeze()
# Condition. Basis covariances get special treatment. See documentation for formulas.
if self.observed and observed:
M = self.C._obs_eval(self, M, x, Uo_Cxo)
return M.reshape(orig_shape)
def __call__(self, x, regularize=True):
# TODO: check repeats for basis covariances too.
# If initial values were passed in, observe on them.
if self.need_init_obs:
self._init_obs()
# Record original shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape) > 1:
orig_shape = orig_shape[:-1]
if regularize:
if any(isnan(x)):
raise ValueError, 'Input argument to Realization contains NaNs.'
x = regularize_array(x)
if x is self.x_sofar:
return self.f_sofar
if self.check_repeats:
# use caching_call to save duplicate calls.
f, self.x_sofar, self.f_sofar = caching_call(
self.draw_vals, x, self.x_sofar, self.f_sofar)
else:
# Call to self.draw_vals.
f = self.draw_vals(x)
if regularize:
return f.reshape(orig_shape)
else:
return f
def cholesky(self,
x,
apply_pivot=True,
observed=True,
nugget=None,
regularize=True):
__doc__ = Covariance.cholesky.__doc__
if regularize:
x = regularize_array(x)
# The pivots are just 1:N, N being the shape of x.
piv_return = arange(x.shape[1], dtype=int)
# The rank of the Cholesky factor is just the rank of the
# coefficient covariance matrix.
if observed:
coef_U = self.coef_U
m = self.m
else:
coef_U = self.unobs_coef_U
m = self.unobs_m
# The Cholesky factor is the Cholesky factor of the basis times
# the basis evaluated on x. This isn't triangular, but it does have
# the property U.T*U = self(x,x).
U_return = asmatrix(self.eval_basis(x, regularize=False))
U_return = coef_U * U_return
if apply_pivot:
# Good for users.
return U_return
else:
# Good for self.observe.
return {'piv': piv_return, 'U': U_return}
def cholesky(self, x, apply_pivot = True, observed=True, nugget=None, regularize=True):
__doc__ = Covariance.cholesky.__doc__
if regularize:
x = regularize_array(x)
# The pivots are just 1:N, N being the shape of x.
piv_return = arange(x.shape[1], dtype=int)
# The rank of the Cholesky factor is just the rank of the
# coefficient covariance matrix.
if observed:
coef_U = self.coef_U
m = self.m
else:
coef_U = self.unobs_coef_U
m = self.unobs_m
# The Cholesky factor is the Cholesky factor of the basis times
# the basis evaluated on x. This isn't triangular, but it does have
# the property U.T*U = self(x,x).
U_return = asmatrix(self.eval_basis(x, regularize=False))
U_return = coef_U * U_return
if apply_pivot:
# Good for users.
return U_return
else:
# Good for self.observe.
return {'piv': piv_return, 'U': U_return}
def __call__(self, x, regularize=True):
# TODO: check repeats for basis covariances too.
# TODO: Do the timing trick down through this method to see where the bottleneck is.
# Record original shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape)>1:
orig_shape = orig_shape[:-1]
if regularize:
if any(isnan(x)):
raise ValueError, 'Input argument to Realization contains NaNs.'
x = regularize_array(x)
if x is self.x_sofar:
return self.f_sofar
if self.check_repeats:
# use caching_call to save duplicate calls.
f, self.x_sofar, self.f_sofar = caching_call(self.draw_vals, x, self.x_sofar, self.f_sofar)
else:
# Call to self.draw_vals.
f = self.draw_vals(x)
if regularize:
return f.reshape(orig_shape)
else:
return f
def __call__(self, x, regularize=True):
# TODO: check repeats for basis covariances too.
# If initial values were passed in, observe on them.
if self.need_init_obs:
self._init_obs()
# Record original shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape)>1:
orig_shape = orig_shape[:-1]
if regularize:
if any(isnan(x)):
raise ValueError, 'Input argument to Realization contains NaNs.'
x = regularize_array(x)
if x is self.x_sofar:
return self.f_sofar
if self.check_repeats:
# use caching_call to save duplicate calls.
f, self.x_sofar, self.f_sofar = caching_call(self.draw_vals, x, self.x_sofar, self.f_sofar)
else:
# Call to self.draw_vals.
f = self.draw_vals(x)
if regularize:
return f.reshape(orig_shape)
else:
return f
def eval_basis(self, x, regularize=True):
"""
basis_mat = C.eval_basis(x)
Evaluates self's basis functions on x and returns them stacked
in a matrix. basis_mat[i,j] gives basis function i (formed by
multiplying basis functions) evaluated at x[j,:].
"""
# Make object of same shape as self.basis, fill in with evals of each individual basis factor.
# Make object of same shape as diag(coef_cov), fill in with products of those evals.
# Reshape and return.
if regularize:
x = regularize_array(x)
out = zeros(self.shape+(x.shape[0],), dtype=float,order='F')
# Evaluate the basis factors
basis_factors = []
for i in xrange(self.ndim):
basis_factors.append([])
for j in xrange(self.n_per_dim[i]):
basis_factors[i].append(self.basis[i][j](x, **self.params))
out = ones((self.n, x.shape[0]), dtype=float)
out_reshaped = out.reshape(self.shape + (x.shape[0],))
for ind in ndindex(self.shape):
for dim in xrange(self.ndim):
out_reshaped[ind] *= basis_factors[dim][ind[dim]]
return out
def __call__(self, x, observed=True, regularize=True):
# Record original shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape) > 1:
orig_shape = orig_shape[:-1]
if regularize:
x = regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
# Safety.
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x does not match the number of spatial dimensions of the Mean instance's base mesh."
# Evaluate the unobserved mean
M = self.eval_fun(x, **self.params).squeeze()
# Condition. Basis covariances get special treatment. See documentation for formulas.
if self.observed and observed:
M = self.C._obs_eval(self, M, x)
return M.reshape(orig_shape)
def eval_basis(self, x, regularize=True):
"""
basis_mat = C.eval_basis(x)
Evaluates self's basis functions on x and returns them stacked
in a matrix. basis_mat[i,j] gives basis function i (formed by
multiplying basis functions) evaluated at x[j,:].
"""
# Make object of same shape as self.basis, fill in with evals of each individual basis factor.
# Make object of same shape as diag(coef_cov), fill in with products of those evals.
# Reshape and return.
if regularize:
x = regularize_array(x)
out = zeros(self.shape + (x.shape[0], ), dtype=float, order='F')
# Evaluate the basis factors
basis_factors = []
for i in xrange(self.ndim):
basis_factors.append([])
for j in xrange(self.n_per_dim[i]):
basis_factors[i].append(self.basis[i][j](x, **self.params))
out = ones((self.n, x.shape[0]), dtype=float)
out_reshaped = out.reshape(self.shape + (x.shape[0], ))
for ind in ndindex(self.shape):
for dim in xrange(self.ndim):
out_reshaped[ind] *= basis_factors[dim][ind[dim]]
return out
def eval_basis(self, x, regularize=True):
"""
basis_mat = C.eval_basis(x)
Evaluates self's basis functions on x and returns them stacked
in a matrix. basis_mat[i,j] gives basis function i evaluated at
x[j,:].
"""
if regularize:
x = regularize_array(x)
out = zeros((self.n, x.shape[0]), dtype=float, order='F')
for i in xrange(self.n):
out[i] = self.basis[i](x, **self.params)
return out
def eval_basis(self, x, regularize = True):
"""
basis_mat = C.eval_basis(x)
Evaluates self's basis functions on x and returns them stacked
in a matrix. basis_mat[i,j] gives basis function i evaluated at
x[j,:].
"""
if regularize:
x = regularize_array(x)
out = zeros((self.n, x.shape[0]), dtype=float, order='F')
for i in xrange(self.n):
out[i] = self.basis[i](x, **self.params)
return out
def __init__(self, M, C, init_mesh = None, init_vals = None, check_repeats = True, regularize = True):
# Make internal copies of M and C. Note that subsequent observations of M and C
# will not affect self.
M_internal = copy.copy(M)
C_internal = copy.copy(C)
M_internal.C = C_internal
# If initial values were specified on a mesh:
if init_mesh is not None:
if regularize:
init_mesh = regularize_array(init_mesh)
init_vals = init_vals.ravel()
# Observe internal M and C with self's value on init_mesh.
observe(M_internal,
C_internal,
obs_mesh=init_mesh,
obs_vals=init_vals,
obs_V=zeros(len(init_vals),dtype=float),
lintrans=None,
cross_validate = False)
# Store init_mesh.
if check_repeats:
self.x_sofar = init_mesh
self.f_sofar = init_vals
elif check_repeats:
# Store init_mesh.
self.x_sofar = None
self.f_sofar = None
self.check_repeats = check_repeats
self.M_internal = M_internal
self.C_internal = C_internal
def _init_obs(self):
# If initial values were specified on a mesh:
if self.init_mesh is not None:
if self.regularize:
self.init_mesh = regularize_array(self.init_mesh)
self.init_vals = self.init_vals.ravel()
# Observe internal M and C with self's value on init_mesh.
observe(self.M_internal,
self.C_internal,
obs_mesh=self.init_mesh,
obs_vals=self.init_vals,
obs_V=zeros(len(self.init_vals),dtype=float),
lintrans=None,
cross_validate = False)
# Store init_mesh.
if self.check_repeats:
self.x_sofar = self.init_mesh
self.f_sofar = self.init_vals
self.need_init_obs = False
def _init_obs(self):
# If initial values were specified on a mesh:
if self.init_mesh is not None:
if self.regularize:
self.init_mesh = regularize_array(self.init_mesh)
self.init_vals = self.init_vals.ravel()
# Observe internal M and C with self's value on init_mesh.
observe(self.M_internal,
self.C_internal,
obs_mesh=self.init_mesh,
obs_vals=self.init_vals,
obs_V=zeros(len(self.init_vals), dtype=float),
lintrans=None,
cross_validate=False)
# Store init_mesh.
if self.check_repeats:
self.x_sofar = self.init_mesh
self.f_sofar = self.init_vals
self.need_init_obs = False
def continue_cholesky(self, x, x_old, chol_dict_old, apply_pivot = True, observed=True, nugget=None, regularize=True, assume_full_rank = False, rank_limit=0):
"""
U = C.continue_cholesky(x, x_old, chol_dict_old[, observed=True, nugget=None,
rank_limit=0])
returns {'pivots': piv, 'U': U}
Computes incomplete Cholesky factorization of self(z,z), without
actually evaluating the matrix first. Here z is the concatenation of x
and x_old. Assumes the Cholesky factorization of self(x_old, x_old) has
already been computed.
:Arguments:
- `x`: The input array on which to evaluate the Cholesky factorization.
- `x_old`: The input array on which the Cholesky factorization has been
computed.
- `chol_dict_old`: A dictionary with kbasis_ys ['pivots', 'U']. Would be the
output of either this method or C.cholesky().
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
- `rank_limit`: If rank_limit > 0, the factor will have at most
rank_limit rows.
"""
if regularize:
x=regularize_array(x)
# Concatenation of the old points and new points.
xtot = vstack((x_old,x))
# Extract information from chol_dict_old.
U_old = chol_dict_old['U']
m_old = U_old.shape[0]
piv_old = chol_dict_old['pivots']
# Number of old points.
N_old = x_old.shape[0]
# Number of new points.
N_new = x.shape[0]
if rank_limit == 0:
m_new_max = N_new
else:
m_new_max = min(N_new,max(0,rank_limit-m_old))
# get-row function
def rowfun(i,xpiv,rowvec):
"""
A function that can be used to overwrite an input array with superdiagonal rows.
"""
rowvec[i:] = self.__call__(x=xpiv[i-1,:].reshape(1,-1), y=xpiv[i:,:], regularize=False, observed = observed)
# diagonal
diag = self.__call__(x, y=None, regularize=False, observed = observed)
# not really implemented yet.
if nugget is not None:
diag += nugget.ravel()
# Arrange U for input to ichol. See documentation.
U = asmatrix(zeros((m_new_max + m_old, N_old + N_new), dtype=float, order='F'))
U[:m_old, :m_old] = U_old[:,:m_old]
U[:m_old,N_new+m_old:] = U_old[:,m_old:]
offdiag = self.__call__(x=x_old[piv_old[:m_old],:], y=x, observed=observed, regularize=False)
trisolve(U_old[:,:m_old],offdiag,uplo='U',transa='T', inplace=True)
U[:m_old, m_old:N_new+m_old] = offdiag
# Initialize pivot vector:
# [old_posdef_pivots new_pivots old_singular_pivots]
# - old_posdef_pivots are the indices of the rows that made it into the Cholesky factor so far.
# - old_singular_pivots are the indices of the rows that haven't made it into the Cholesky factor so far.
# - new_pivots are the indices of the rows that are going to be incorporated now.
piv = zeros(N_new + N_old, dtype=int)
piv[:m_old] = piv_old[:m_old]
piv[N_new + m_old:] = piv_old[m_old:]
piv[m_old:N_new + m_old] = arange(N_new)+N_old
# ============================================
# = Call to Fortran function ichol_continue. =
# ============================================
# Early return if rank is all used up.
if m_new_max > 0:
# ============================================
# = Call to Fortran function ichol_continue. =
# ============================================
if not assume_full_rank:
m, piv = ichol_continue(U, diag = diag, reltol = self.relative_precision, rowfun = rowfun, piv=piv, x=xtot[piv,:], mold=m_old)
else:
m = m_old + N_new
C_eval = self.__call__(x,x,observed=True,regularize=False)
U2 = cholesky(C_eval).T
U[m_old:,m_old:N_new+m_old] = U2
if m_old < N_old:
offdiag2 = self.__call__(x=x, y=x_old[piv_old[m_old:]], observed=observed, regularize=False)
trisolve(U2,offdiag2,uplo='U',transa='T',inplace=True)
U[m_old:,N_new+m_old:] = offdiag2
else:
m = m_old
# Arrange output matrix and return.
if m<0:
raise ValueError, 'Matrix does not appear positive semidefinite.'
if not apply_pivot:
# Useful for self.observe. U is upper triangular.
U = U[:m,:]
if assume_full_rank:
return {'pivots': piv, 'U': U, 'C_eval':C_eval, 'U_new': U2}
else:
return {'pivots': piv, 'U': U}
else:
# Useful for the user. U.T * U = C(x,x).
return U[:m,argsort(piv)]
def __call__(self, x, y=None, observed=True, regularize=True):
# Record the initial shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape)>1:
orig_shape = orig_shape[:-1]
if regularize:
x=regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
# Get the correct version of the Cholesky factor of the coefficient covariance.
if observed:
coef_U = self.coef_U
else:
coef_U = self.unobs_coef_U
# Safety.
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x does not match the number of spatial dimensions of the Covariance instance's base mesh."
# Evaluate the Cholesky factor of self's evaluation on x.
# Will be observed or not depending on which version of coef_U
# is used.
basis_x = self.eval_basis(x, regularize=False)
basis_x = coef_U*basis_x
# ==========================================================
# = If only one argument is provided, return the diagonal: =
# ==========================================================
if y is None:
# Diagonal calls done in Fortran for speed.
V = basis_diag_call(basis_x)
return V.reshape(orig_shape)
# ===========================================================
# = If the same argument is provided twice, save some work: =
# ===========================================================
if y is x:
return basis_x.T*basis_x
# =========================================
# = If y and x are different, do needful: =
# =========================================
else:
# Regularize y and record its original shape.
if regularize:
y=regularize_array(y)
ndimy = y.shape[-1]
leny = y.shape[0]
if not ndimx==ndimy:
raise ValueError, 'The last dimension of x and y (the number of spatial dimensions) must be the same.'
# Evaluate the Cholesky factor of self's evaluation on y.
# Will be observed or not depending on which version of coef_U
# is used.
basis_y = self.eval_basis(y, regularize=False)
basis_y = coef_U*basis_y
return basis_x.T*basis_y
def __call__(self, x, y=None, observed=True, regularize=True):
if y is x:
symm=True
else:
symm=False
# Remember shape of x, and then 'regularize' it.
orig_shape = shape(x)
if len(orig_shape)>1:
orig_shape = orig_shape[:-1]
if regularize:
x=regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
# Safety
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x, "+\
ndimx.__str__()+\
", does not match the number of spatial dimensions of the Covariance instance's base mesh, "+\
self.ndim.__str__()+"."
# If there are observation points, prepare self(obs_mesh, x)
# and chol(self(obs_mesh, obs_mesh)).T.I * self(obs_mesh, x)
if self.observed and observed:
Cxo = self.eval_fun(self.obs_mesh, x, **self.params)
Uo_Cxo = trisolve(self.Uo, Cxo, uplo='U', transa='T')
# ==========================================================
# = If only one argument is provided, return the diagonal. =
# ==========================================================
# See documentation.
if y is None:
# V = diag_call(x=x, cov_fun = self.diag_cov_fun)
# =============================================================================
# = Come up with a better solution, the diagonal is not necessarily constant. =
# =============================================================================
V=empty(lenx,dtype=float)
# V.fill(self.params['amp']**2)
for i in xrange(lenx):
this_x = x[i].reshape((1,-1))
V[i] = self.eval_fun(this_x, this_x,**self.params)
if self.observed and observed:
for i in range(lenx):
this_Uo_Cxo = Uo_Cxo[:,i]
V[i] -= this_Uo_Cxo.T*this_Uo_Cxo
return V.reshape(orig_shape)
else:
# ====================================================
# = # If x and y are the same array, save some work: =
# ====================================================
if symm:
C=self.eval_fun(x,x,symm=True,**self.params)
# Update return value using observations.
if self.observed and observed:
C -= Uo_Cxo.T * Uo_Cxo
return C
# ======================================
# = # If x and y are different arrays: =
# ======================================
else:
if regularize:
y=regularize_array(y)
ndimy = y.shape[-1]
leny = y.shape[0]
if not ndimx==ndimy:
raise ValueError, 'The last dimension of x and y (the number of spatial dimensions) must be the same.'
C = self.eval_fun(x,y,**self.params)
# Update return value using observations.
if self.observed and observed:
# If there are observation points, prepare self(obs_mesh, y)
# and chol(self(obs_mesh, obs_mesh)).T.I * self(obs_mesh, y)
Cyo = self.eval_fun(self.obs_mesh, y, **self.params)
Uo_Cyo = trisolve(self.Uo, Cyo,uplo='U', transa='T')
C -= Uo_Cxo.T * Uo_Cyo
return C
def cholesky(self, x, apply_pivot = True, observed=True, nugget=None, regularize=True, rank_limit=0):
"""
U = C.cholesky(x[, observed=True, nugget=None, rank_limit=0])
{'pivots': piv, 'U': U} = \
C.cholesky(x, apply_pivot = False[, observed=True, nugget=None])
Computes incomplete Cholesky factorization of self(x,x).
:Arguments:
- `x`: The input array on which to evaluate the covariance.
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
- `rank_limit`: If rank_limit > 0, the factor will have at most
rank_limit rows.
"""
if rank_limit > 0:
raise ValueError, 'NearlyFullRankCovariance does not accept a rank_limit argument. Use Covariance instead.'
if regularize:
x=regularize_array(x)
# Number of points in x.
N_new = x.shape[0]
# Special fast version for single points.
if N_new==1:
V = self.__call__(x, regularize = False, observed = observed)
if nugget is not None:
V += nugget
U=asmatrix(sqrt(V))
# print U
if not apply_pivot:
return {'pivots': array([0]), 'U': U}
else:
return U
C = self.__call__(x, x, regularize=False, observed=observed)
if nugget is not None:
for i in xrange(N_new):
C[i,i] += nugget[i]
# =======================================
# = Call to Fortran function ichol_full =
# =======================================
U, m, piv = ichol_full(c=C, reltol=self.relative_precision)
U = asmatrix(U)
# Arrange output matrix and return.
if m<0:
raise ValueError, "Matrix does not appear to be positive semidefinite"
if not apply_pivot:
# Useful for self.observe and Realization.__call__. U is upper triangular.
U = U[:m,:]
return {'pivots': piv, 'U': U}
else:
# Useful for users. U.T*U = C(x,x)
return U[:m,argsort(piv)]
def obs_mesh(obs_mesh=obs_mesh):
return regularize_array(obs_mesh)
def __init__(self,
name,
M,
C,
mesh=None,
doc="A GP realization-valued stochastic variable",
init_mesh_vals = None,
mesh_eval_observed = False,
trace=True,
cache_depth=2,
verbose=False):
self.conjugate=True
if not isinstance(mesh, np.ndarray) and mesh is not None:
raise ValueError, name + ": __init__ argument 'mesh' must be ndarray."
self.mesh = regularize_array(mesh)
# Safety
if isinstance(M, pm.Deterministic):
if not isinstance(M.value, Mean):
raise ValueError, 'GP' + self.__name__ + ': Argument M must be Mean instance '+\
'or pm.Deterministic valued as Mean instance, got pm.Deterministic valued as ' + M.__class__.__name__
elif not isinstance(M, Mean):
raise ValueError, 'GP' + self.__name__ + ': Argument M must be Mean instance '+\
'or pm.Deterministic valued as Mean instance, got ' + M.__class__.__name__
if isinstance(C, pm.Deterministic):
if not isinstance(C.value, Covariance):
raise ValueError, 'GP' + self.__name__ + ': Argument C must be Covariance instance '+\
'or pm.Deterministic valued as Covariance instance, got pm.Deterministic valued as ' + C.__class__.__name__
elif not isinstance(C, Covariance):
raise ValueError, 'GP' + self.__name__ + ': Argument C must be Covariance instance '+\
'or pm.Deterministic valued as Covariance instance, got ' + C.__class__.__name__
# This function will be used to draw values for self conditional on self's parents.
def random_fun(M,C):
return Realization(M,C)
self._random = random_fun
if self.mesh is not None:
self.mesh = regularize_array(self.mesh)
@pm.deterministic(verbose=verbose-1, cache_depth=cache_depth, trace=False)
def M_mesh(M=M, mesh=self.mesh):
"""
The mean function evaluated on the mesh,
cached for speed.
"""
return M(mesh, regularize=False)
M_mesh.__name__ = name + '_M_mesh'
@pm.deterministic(verbose=verbose-1, cache_depth=cache_depth, trace=False)
def C_and_U_mesh(C=C, mesh=self.mesh):
"""
The upper-triangular Cholesky factor of the
covariance function evaluated on the mesh,
cached for speed.
"""
# TODO: Will need to change this when sparse covariances
# are available. dpotrf doesn't know about sparse covariances.
C_old = C
C = copy.copy(C)
# Most covariances generate U_mesh automatically when observed,
# and after observation they can be used to efficiently construct realizations.
try:
junk1, junk2, U = C.observe(mesh, np.zeros(mesh.shape[0]), assume_full_rank=True)
except np.linalg.LinAlgError:
return np.linalg.LinAlgError
# Handle BasisCovariances separately
if U is None:
try:
U = np.linalg.cholesky(C_old(mesh,mesh,regularize=False)).T
except np.linalg.LinAlgError:
return np.linalg.LinAlgError
# print U.T*U - C_old(mesh,mesh,regularize=False)
if U.shape[0] < U.shape[1]:
return np.linalg.LinAlgError
return U, C
C_and_U_mesh.__name__ = name + 'C_and_U_mesh'
self.M_mesh = M_mesh
self.C_and_U_mesh = C_and_U_mesh
def logp_fun(value, M, C):
if self.mesh is None:
if self.verbose > 1:
print '\t%s: No mesh, returning 0.' % self.__name__
return 0.
elif self.C_and_U_mesh.value is np.linalg.LinAlgError:
if self.verbose > 1:
print '\t%s: Covariance not positive definite on mesh, returning -infinity.' % self.__name__
return -np.Inf
else:
if self.verbose > 1:
print '\t%s: Computing log-probability.' % self.__name__
return linalg_utils.gp_array_logp(value(self.mesh), self.M_mesh.value, self.C_and_U_mesh.value[0])
@pm.deterministic(verbose=verbose-1, cache_depth=cache_depth, trace=False)
def init_val(M=M, C=C, init_mesh = self.mesh, init_mesh_vals = init_mesh_vals):
if init_mesh_vals is not None:
return Realization(M, C, init_mesh, init_mesh_vals.ravel(), regularize=False)
else:
return Realization(M, C)
init_val.__name__ = name + '_init_val'
pm.Stochastic.__init__( self,
logp=logp_fun,
doc=doc,
name=name,
parents={'M': M, 'C': C},
dtype=np.dtype('object'),
random = random_fun,
trace=trace,
value=init_val.value,
observed=False,
cache_depth=cache_depth,
verbose = verbose)
def continue_cholesky(self, x, x_old, chol_dict_old, apply_pivot = True, observed=True, nugget=None, regularize=True, assume_full_rank=False):
"""
U = C.continue_cholesky(x, x_old, chol_dict_old[, observed=True, nugget=None])
{'pivots': piv, 'U': U} = \
C.cholesky(x, x_old, chol_dict_old, apply_pivot = False[, observed=True, nugget=None])
Computes incomplete Cholesky factorization of self(z,z). Here z is the
concatenation of x and x_old. Assumes the Cholesky factorization of
self(x_old, x_old) has already been computed.
:Arguments:
- `x`: The input array on which to evaluate the Cholesky factorization.
- `x_old`: The input array on which the Cholesky factorization has been
computed.
- `chol_dict_old`: A dictionary with kbasis_ys ['pivots', 'U']. Would be the
output of either this method or C.cholesky().
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
"""
if regularize:
x=regularize_array(x)
# Concatenation of the old points and new points.
xtot = vstack((x_old,x))
# Extract information from chol_dict_old.
U_old = chol_dict_old['U']
m_old = U_old.shape[0]
piv_old = chol_dict_old['pivots']
# Number of old points.
N_old = x_old.shape[0]
# Number of new points.
N_new = x.shape[0]
# Compute off-diagonal part of Cholesky factor
offdiag = self.__call__(x=x_old[piv_old[:m_old],:], y=x, observed=observed, regularize=False)
trisolve(U_old[:,:m_old],offdiag,uplo='U',transa='T', inplace=True)
# Compute new diagonal part of Cholesky factor
C_new = self.__call__(x=x, y=x, observed=observed, regularize=False)
if nugget is not None:
for i in xrange(N_new):
C_new[i,i] += nugget[i]
C_new -= offdiag.T*offdiag
if not assume_full_rank:
U_new, m_new, piv_new = ichol_full(c=C_new, reltol=self.relative_precision)
else:
U_new = cholesky(C_new).T
m_new = U_new.shape[0]
piv_new = arange(m_new)
U_new = asmatrix(U_new[:m_new,:])
U = asmatrix(zeros((m_new + m_old, N_old + N_new), dtype=float, order='F'))
# Top portion of U
U[:m_old, :m_old] = U_old[:,:m_old]
U[:m_old,N_new+m_old:] = U_old[:,m_old:]
offdiag=offdiag[:,piv_new]
U[:m_old, m_old:N_new+m_old] = offdiag
# Lower portion of U
U[m_old:,m_old:m_old+N_new] = U_new
if m_old < N_old and m_new > 0:
offdiag_lower = self.__call__( x=x[piv_new[:m_new],:],
y=x_old[piv_old[m_old:],:], observed=observed, regularize=False)
offdiag_lower -= offdiag[:,:m_new].T*U[:m_old,m_old+N_new:]
trisolve(U_new[:,:m_new],offdiag_lower,uplo='U',transa='T', inplace=True)
U[m_old:,m_old+N_new:] = offdiag_lower
# Rank and pivots
m=m_old+m_new
piv=hstack((piv_old[:m_old],piv_new+N_old,piv_old[m_old:]))
# Arrange output matrix and return.
if m<0:
raise ValueError, 'Matrix does not appear positive semidefinite.'
if not apply_pivot:
# Useful for self.observe. U is upper triangular.
return {'pivots': piv, 'U': U}
else:
# Useful for the user. U.T * U = C(x,x).
return U[:,argsort(piv)]
def __call__(self,
x,
y=None,
observed=True,
regularize=True,
return_Uo_Cxo=False):
if y is x:
symm = True
else:
symm = False
# Remember shape of x, and then 'regularize' it.
orig_shape = shape(x)
if len(orig_shape) > 1:
orig_shape = orig_shape[:-1]
if regularize:
x = regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
if return_Uo_Cxo:
Uo_Cxo = None
# Safety
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x, "+\
ndimx.__str__()+\
", does not match the number of spatial dimensions of the Covariance instance's base mesh, "+\
self.ndim.__str__()+"."
# If there are observation points, prepare self(obs_mesh, x)
# and chol(self(obs_mesh, obs_mesh)).T.I * self(obs_mesh, x)
# ==========================================================
# = If only one argument is provided, return the diagonal. =
# ==========================================================
if y is None:
# Special fast-path for functions that have an 'amp' parameter
if hasattr(self.eval_fun, 'diag_call'):
V = self.eval_fun.diag_call(x, **self.params)
# Otherwise, evaluate the diagonal in a loop.
else:
V = empty(lenx, dtype=float)
for i in xrange(lenx):
this_x = x[i].reshape((1, -1))
V[i] = self.eval_fun(this_x, this_x, **self.params)
if self.observed and observed:
sqpart = empty(lenx, dtype=float)
Cxo = self.eval_fun(self.obs_mesh, x, **self.params)
Uo_Cxo = trisolve(self.Uo, Cxo, uplo='U', transa='T')
square_and_sum(Uo_Cxo, sqpart)
V -= sqpart
if return_Uo_Cxo:
return V.reshape(orig_shape), Uo_Cxo
else:
return V.reshape(orig_shape)
else:
# ====================================================
# = # If x and y are the same array, save some work: =
# ====================================================
if symm:
C = self.eval_fun(x, x, symm=True, **self.params)
# Update return value using observations.
if self.observed and observed:
Cxo = self.eval_fun(self.obs_mesh, x, **self.params)
Uo_Cxo = trisolve(self.Uo, Cxo, uplo='U', transa='T')
C -= Uo_Cxo.T * Uo_Cxo
if return_Uo_Cxo:
return C, Uo_Cxo
else:
return C
# ======================================
# = # If x and y are different arrays: =
# ======================================
else:
if regularize:
y = regularize_array(y)
ndimy = y.shape[-1]
leny = y.shape[0]
if not ndimx == ndimy:
raise ValueError, 'The last dimension of x and y (the number of spatial dimensions) must be the same.'
C = self.eval_fun(x, y, **self.params)
# Update return value using observations.
if self.observed and observed:
# If there are observation points, prepare self(obs_mesh, y)
# and chol(self(obs_mesh, obs_mesh)).T.I * self(obs_mesh, y)
Cyo = self.eval_fun(self.obs_mesh, y, **self.params)
Uo_Cyo = trisolve(self.Uo, Cyo, uplo='U', transa='T')
C -= Uo_Cxo.T * Uo_Cyo
return C
def __call__(self,
x,
y=None,
observed=True,
regularize=True,
return_Uo_Cxo=False):
# Record the initial shape of x and regularize it.
orig_shape = shape(x)
if len(orig_shape) > 1:
orig_shape = orig_shape[:-1]
if regularize:
x = regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
# Get the correct version of the Cholesky factor of the coefficient covariance.
if observed:
coef_U = self.coef_U
else:
coef_U = self.unobs_coef_U
# Safety.
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x does not match the number of spatial dimensions of the Covariance instance's base mesh."
# Evaluate the Cholesky factor of self's evaluation on x.
# Will be observed or not depending on which version of coef_U
# is used.
basis_x_ = self.eval_basis(x, regularize=False)
basis_x = coef_U * basis_x_
# ==========================================================
# = If only one argument is provided, return the diagonal: =
# ==========================================================
if y is None:
# Diagonal calls done in Fortran for speed.
V = basis_diag_call(basis_x)
if return_Uo_Cxo:
return V.reshape(orig_shape), basis_x_
else:
return V.reshape(orig_shape)
# ===========================================================
# = If the same argument is provided twice, save some work: =
# ===========================================================
if y is x:
if return_Uo_Cxo:
return basis_x.T * basis_x, basis_x_
else:
return basis_x
# =========================================
# = If y and x are different, do needful: =
# =========================================
else:
# Regularize y and record its original shape.
if regularize:
y = regularize_array(y)
ndimy = y.shape[-1]
leny = y.shape[0]
if not ndimx == ndimy:
raise ValueError, 'The last dimension of x and y (the number of spatial dimensions) must be the same.'
# Evaluate the Cholesky factor of self's evaluation on y.
# Will be observed or not depending on which version of coef_U
# is used.
basis_y = self.eval_basis(y, regularize=False)
basis_y = coef_U * basis_y
return basis_x.T * basis_y
def continue_cholesky(self,
x,
x_old,
chol_dict_old,
apply_pivot=True,
observed=True,
nugget=None,
regularize=True,
assume_full_rank=False,
rank_limit=0):
"""
U = C.continue_cholesky(x, x_old, chol_dict_old[, observed=True, nugget=None,
rank_limit=0])
returns {'pivots': piv, 'U': U}
Computes incomplete Cholesky factorization of self(z,z), without
actually evaluating the matrix first. Here z is the concatenation of x
and x_old. Assumes the Cholesky factorization of self(x_old, x_old) has
already been computed.
:Arguments:
- `x`: The input array on which to evaluate the Cholesky factorization.
- `x_old`: The input array on which the Cholesky factorization has been
computed.
- `chol_dict_old`: A dictionary with kbasis_ys ['pivots', 'U']. Would be the
output of either this method or C.cholesky().
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
- `rank_limit`: If rank_limit > 0, the factor will have at most
rank_limit rows.
"""
if regularize:
x = regularize_array(x)
# Concatenation of the old points and new points.
xtot = vstack((x_old, x))
# Extract information from chol_dict_old.
U_old = chol_dict_old['U']
m_old = U_old.shape[0]
piv_old = chol_dict_old['pivots']
# Number of old points.
N_old = x_old.shape[0]
# Number of new points.
N_new = x.shape[0]
if rank_limit == 0:
m_new_max = N_new
else:
m_new_max = min(N_new, max(0, rank_limit - m_old))
# get-row function
def rowfun(i, xpiv, rowvec):
"""
A function that can be used to overwrite an input array with superdiagonal rows.
"""
rowvec[i:] = self.__call__(x=xpiv[i - 1, :].reshape(1, -1),
y=xpiv[i:, :],
regularize=False,
observed=observed)
# diagonal
diag = self.__call__(x, y=None, regularize=False, observed=observed)
# not really implemented yet.
if nugget is not None:
diag += nugget.ravel()
# Arrange U for input to ichol. See documentation.
U = asmatrix(
zeros((m_new_max + m_old, N_old + N_new), dtype=float, order='F'))
U[:m_old, :m_old] = U_old[:, :m_old]
U[:m_old, N_new + m_old:] = U_old[:, m_old:]
offdiag = self.__call__(x=x_old[piv_old[:m_old], :],
y=x,
observed=observed,
regularize=False)
trisolve(U_old[:, :m_old], offdiag, uplo='U', transa='T', inplace=True)
U[:m_old, m_old:N_new + m_old] = offdiag
# Initialize pivot vector:
# [old_posdef_pivots new_pivots old_singular_pivots]
# - old_posdef_pivots are the indices of the rows that made it into the Cholesky factor so far.
# - old_singular_pivots are the indices of the rows that haven't made it into the Cholesky factor so far.
# - new_pivots are the indices of the rows that are going to be incorporated now.
piv = zeros(N_new + N_old, dtype=int)
piv[:m_old] = piv_old[:m_old]
piv[N_new + m_old:] = piv_old[m_old:]
piv[m_old:N_new + m_old] = arange(N_new) + N_old
# ============================================
# = Call to Fortran function ichol_continue. =
# ============================================
# Early return if rank is all used up.
if m_new_max > 0:
# ============================================
# = Call to Fortran function ichol_continue. =
# ============================================
if not assume_full_rank:
m, piv = ichol_continue(U,
diag=diag,
reltol=self.relative_precision,
rowfun=rowfun,
piv=piv,
x=xtot[piv, :],
mold=m_old)
else:
m = m_old + N_new
C_eval = self.__call__(x, x, observed=True, regularize=False)
U2 = cholesky(C_eval).T
U[m_old:, m_old:N_new + m_old] = U2
if m_old < N_old:
offdiag2 = self.__call__(x=x,
y=x_old[piv_old[m_old:]],
observed=observed,
regularize=False)
trisolve(U2, offdiag2, uplo='U', transa='T', inplace=True)
U[m_old:, N_new + m_old:] = offdiag2
else:
m = m_old
# Arrange output matrix and return.
if m < 0:
raise ValueError, 'Matrix does not appear positive semidefinite.'
if not apply_pivot:
# Useful for self.observe. U is upper triangular.
U = U[:m, :]
if assume_full_rank:
return {'pivots': piv, 'U': U, 'C_eval': C_eval, 'U_new': U2}
else:
return {'pivots': piv, 'U': U}
else:
# Useful for the user. U.T * U = C(x,x).
return U[:m, argsort(piv)]
def __call__(self, x, y=None, observed=True, regularize=True, return_Uo_Cxo=False):
if y is x:
symm=True
else:
symm=False
# Remember shape of x, and then 'regularize' it.
orig_shape = shape(x)
if len(orig_shape)>1:
orig_shape = orig_shape[:-1]
if regularize:
x=regularize_array(x)
ndimx = x.shape[-1]
lenx = x.shape[0]
if return_Uo_Cxo:
Uo_Cxo = None
# Safety
if self.ndim is not None:
if not self.ndim == ndimx:
raise ValueError, "The number of spatial dimensions of x, "+\
ndimx.__str__()+\
", does not match the number of spatial dimensions of the Covariance instance's base mesh, "+\
self.ndim.__str__()+"."
# If there are observation points, prepare self(obs_mesh, x)
# and chol(self(obs_mesh, obs_mesh)).T.I * self(obs_mesh, x)
# ==========================================================
# = If only one argument is provided, return the diagonal. =
# ==========================================================
if y is None:
# Special fast-path for functions that have an 'amp' parameter
if hasattr(self.eval_fun, 'diag_call'):
V = self.eval_fun.diag_call(x, **self.params)
# Otherwise, evaluate the diagonal in a loop.
else:
V=empty(lenx,dtype=float)
for i in xrange(lenx):
this_x = x[i].reshape((1,-1))
V[i] = self.eval_fun(this_x, this_x, **self.params)
if self.observed and observed:
sqpart = empty(lenx,dtype=float)
Cxo = self.eval_fun(self.obs_mesh, x, **self.params)
Uo_Cxo = trisolve(self.Uo, Cxo, uplo='U', transa='T')
square_and_sum(Uo_Cxo, sqpart)
V -= sqpart
if return_Uo_Cxo:
return V.reshape(orig_shape), Uo_Cxo
else:
return V.reshape(orig_shape)
else:
# ====================================================
# = # If x and y are the same array, save some work: =
# ====================================================
if symm:
C=self.eval_fun(x,x,symm=True,**self.params)
# Update return value using observations.
if self.observed and observed:
Cxo = self.eval_fun(self.obs_mesh, x, **self.params)
Uo_Cxo = trisolve(self.Uo, Cxo, uplo='U', transa='T')
C -= Uo_Cxo.T * Uo_Cxo
if return_Uo_Cxo:
return C, Uo_Cxo
else:
return C
# ======================================
# = # If x and y are different arrays: =
# ======================================
else:
if regularize:
y=regularize_array(y)
ndimy = y.shape[-1]
leny = y.shape[0]
if not ndimx==ndimy:
raise ValueError, 'The last dimension of x and y (the number of spatial dimensions) must be the same.'
C = self.eval_fun(x,y,**self.params)
# Update return value using observations.
if self.observed and observed:
# If there are observation points, prepare self(obs_mesh, y)
# and chol(self(obs_mesh, obs_mesh)).T.I * self(obs_mesh, y)
Cyo = self.eval_fun(self.obs_mesh, y, **self.params)
Uo_Cyo = trisolve(self.Uo, Cyo,uplo='U', transa='T')
C -= Uo_Cxo.T * Uo_Cyo
return C
def cholesky(self,
x,
apply_pivot=True,
observed=True,
nugget=None,
regularize=True,
rank_limit=0):
"""
U = C.cholesky(x[, observed=True, nugget=None, rank_limit=00])
{'pivots': piv, 'U': U} = \
C.cholesky(x, apply_pivot = False[, observed=True, nugget=None])
Computes incomplete Cholesky factorization of self(x,x), without
actually evaluating the matrix first.
:Arguments:
- `x`: The input array on which to evaluate the covariance.
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
- `rank_limit`: If rank_limit > 0, the factor will have at most
rank_limit rows.
"""
if regularize:
x = regularize_array(x)
# Number of points in x.
N_new = x.shape[0]
# diagonal
diag = self.__call__(x, y=None, regularize=False, observed=observed)
if nugget is not None:
diag += nugget.ravel()
# Special fast version for single points.
if N_new == 1:
U = asmatrix(sqrt(diag))
# print U
if not apply_pivot:
return {'pivots': array([0]), 'U': U}
else:
return U
# Create the diagonal and the get-row function differently depending on whether self
# has been observed. If self hasn't been observed, send the calls straight to eval_fun
# to skip the extra formatting.
# get-row function
# TODO: Forbid threading here due to callbacks.
def rowfun(i, xpiv, rowvec):
"""
A function that can be used to overwrite an input array with rows.
"""
rowvec[i:] = self.__call__(x=xpiv[i - 1, :].reshape((1, -1)),
y=xpiv[i:, :],
regularize=False,
observed=observed)
# ==================================
# = Call to Fortran function ichol =
# ==================================
if rank_limit == 0:
rank_limit = N_new
U, m, piv = ichol(diag=diag,
reltol=self.relative_precision,
rowfun=rowfun,
x=x,
rl=min(rank_limit, N_new))
U = asmatrix(U)
# Arrange output matrix and return.
if m < 0:
raise ValueError, "Matrix does not appear to be positive semidefinite"
if not apply_pivot:
# Useful for self.observe and Realization.__call__. U is upper triangular.
U = U[:m, :]
return {'pivots': piv, 'U': U}
else:
# Useful for users. U.T*U = C(x,x)
return U[:m, argsort(piv)]
def cholesky(self, x, apply_pivot = True, observed=True, nugget=None, regularize=True, rank_limit=0):
"""
U = C.cholesky(x[, observed=True, nugget=None, rank_limit=00])
{'pivots': piv, 'U': U} = \
C.cholesky(x, apply_pivot = False[, observed=True, nugget=None])
Computes incomplete Cholesky factorization of self(x,x), without
actually evaluating the matrix first.
:Arguments:
- `x`: The input array on which to evaluate the covariance.
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
- `rank_limit`: If rank_limit > 0, the factor will have at most
rank_limit rows.
"""
if regularize:
x=regularize_array(x)
# Number of points in x.
N_new = x.shape[0]
# diagonal
diag = self.__call__(x, y=None, regularize=False, observed=observed)
if nugget is not None:
diag += nugget.ravel()
# Special fast version for single points.
if N_new==1:
U=asmatrix(sqrt(diag))
# print U
if not apply_pivot:
return {'pivots': array([0]), 'U': U}
else:
return U
# Create the diagonal and the get-row function differently depending on whether self
# has been observed. If self hasn't been observed, send the calls straight to eval_fun
# to skip the extra formatting.
# get-row function
# TODO: Forbid threading here due to callbacks.
def rowfun(i,xpiv,rowvec):
"""
A function that can be used to overwrite an input array with rows.
"""
rowvec[i:]=self.__call__(x=xpiv[i-1,:].reshape((1,-1)), y=xpiv[i:,:], regularize=False, observed=observed)
# ==================================
# = Call to Fortran function ichol =
# ==================================
if rank_limit == 0:
rank_limit = N_new
U, m, piv = ichol(diag=diag, reltol=self.relative_precision, rowfun=rowfun, x=x, rl=min(rank_limit,N_new))
U = asmatrix(U)
# Arrange output matrix and return.
if m<0:
raise ValueError, "Matrix does not appear to be positive semidefinite"
if not apply_pivot:
# Useful for self.observe and Realization.__call__. U is upper triangular.
U = U[:m,:]
return {'pivots': piv, 'U': U}
else:
# Useful for users. U.T*U = C(x,x)
return U[:m,argsort(piv)]
def cholesky(self, x, apply_pivot = True, observed=True, nugget=None, regularize=True):
"""
U = C.cholesky(x[, observed=True, nugget=None])
{'pivots': piv, 'U': U} = \
C.cholesky(x, apply_pivot = False[, observed=True, nugget=None])
Computes incomplete Cholesky factorization of self(x,x).
:Arguments:
- `x`: The input array on which to evaluate the covariance.
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
"""
if regularize:
x=regularize_array(x)
# Number of points in x.
N_new = x.shape[0]
# Special fast version for single points.
if N_new==1:
U=asmatrix(sqrt(self.__call__(x, regularize = False, observed = observed)))
# print U
if not apply_pivot:
return {'pivots': array([0]), 'U': U}
else:
return U
C = self.__call__(x, x, regularize=False, observed=observed)
if nugget is not None:
for i in xrange(N_new):
C[i,i] += nugget[i]
# =======================================
# = Call to Fortran function ichol_full =
# =======================================
U, m, piv = ichol_full(c=C, reltol=self.relative_precision)
U = asmatrix(U)
# Arrange output matrix and return.
if m<0:
raise ValueError, "Matrix does not appear to be positive semidefinite"
if not apply_pivot:
# Useful for self.observe and Realization.__call__. U is upper triangular.
U = U[:m,:]
return {'pivots': piv, 'U': U}
else:
# Useful for users. U.T*U = C(x,x)
return U[:m,argsort(piv)]
def continue_cholesky(self, x, x_old, chol_dict_old, apply_pivot = True, observed=True, nugget=None, regularize=True, assume_full_rank=False, rank_limit=0):
"""
U = C.continue_cholesky(x, x_old, chol_dict_old[, observed=True, nugget=None,
rank_limit=0])
Returns {'pivots': piv, 'U': U}
Computes incomplete Cholesky factorization of self(z,z). Here z is the
concatenation of x and x_old. Assumes the Cholesky factorization of
self(x_old, x_old) has already been computed.
:Arguments:
- `x`: The input array on which to evaluate the Cholesky factorization.
- `x_old`: The input array on which the Cholesky factorization has been
computed.
- `chol_dict_old`: A dictionary with kbasis_ys ['pivots', 'U']. Would be the
output of either this method or C.cholesky().
- `apply_pivot`: A flag. If it's set to 'True', it returns a
matrix U (not necessarily triangular) such that U.T*U=C(x,x).
If it's set to 'False', the return value is a dictionary.
Item 'pivots' is a vector of pivots, and item 'U' is an
upper-triangular matrix (not necessarily square) such that
U[:,argsort(piv)].T * U[:,argsort(piv)] = C(x,x).
- `observed`: If 'True', any observations are taken into account
when computing the Cholesky factor. If not, the unobserved
version of self is used.
- `nugget`: The 'nugget' parameter, which will essentially be
added to the diagonal of C(x,x) before Cholesky factorizing.
- `rank_limit`: If rank_limit > 0, the factor will have at most
rank_limit rows.
"""
if regularize:
x=regularize_array(x)
if rank_limit > 0:
raise ValueError, 'NearlyFullRankCovariance does not accept a rank_limit argument. Use Covariance instead.'
if rank_limit > 0:
raise ValueError, 'NearlyFullRankCovariance does not accept a rank_limit argument. Use Covariance instead.'
# Concatenation of the old points and new points.
xtot = vstack((x_old,x))
# Extract information from chol_dict_old.
U_old = chol_dict_old['U']
m_old = U_old.shape[0]
piv_old = chol_dict_old['pivots']
# Number of old points.
N_old = x_old.shape[0]
# Number of new points.
N_new = x.shape[0]
# Compute off-diagonal part of Cholesky factor
offdiag = self.__call__(x=x_old[piv_old[:m_old],:], y=x, observed=observed, regularize=False)
trisolve(U_old[:,:m_old],offdiag,uplo='U',transa='T', inplace=True)
# Compute new diagonal part of Cholesky factor
C_new = self.__call__(x=x, y=x, observed=observed, regularize=False)
if nugget is not None:
for i in xrange(N_new):
C_new[i,i] += nugget[i]
C_new -= offdiag.T*offdiag
if not assume_full_rank:
U_new, m_new, piv_new = ichol_full(c=C_new, reltol=self.relative_precision)
else:
U_new = cholesky(C_new).T
m_new = U_new.shape[0]
piv_new = arange(m_new)
U_new = asmatrix(U_new[:m_new,:])
U = asmatrix(zeros((m_new + m_old, N_old + N_new), dtype=float, order='F'))
# Top portion of U
U[:m_old, :m_old] = U_old[:,:m_old]
U[:m_old,N_new+m_old:] = U_old[:,m_old:]
offdiag=offdiag[:,piv_new]
U[:m_old, m_old:N_new+m_old] = offdiag
# Lower portion of U
U[m_old:,m_old:m_old+N_new] = U_new
if m_old < N_old and m_new > 0:
offdiag_lower = self.__call__( x=x[piv_new[:m_new],:],
y=x_old[piv_old[m_old:],:], observed=observed, regularize=False)
offdiag_lower -= offdiag[:,:m_new].T*U[:m_old,m_old+N_new:]
trisolve(U_new[:,:m_new],offdiag_lower,uplo='U',transa='T', inplace=True)
U[m_old:,m_old+N_new:] = offdiag_lower
# Rank and pivots
m=m_old+m_new
piv=hstack((piv_old[:m_old],piv_new+N_old,piv_old[m_old:]))
# Arrange output matrix and return.
if m<0:
raise ValueError, 'Matrix does not appear positive semidefinite.'
if not apply_pivot:
# Useful for self.observe. U is upper triangular.
if assume_full_rank:
return {'pivots':piv,'U':U,'C_eval':C_new,'U_new':U_new}
else:
return {'pivots': piv, 'U': U}
else:
# Useful for the user. U.T * U = C(x,x).
return U[:,argsort(piv)]
def obs_mesh(obs_mesh=obs_mesh):
return regularize_array(obs_mesh)
def __init__(self,
name,
M,
C,
mesh=None,
doc="A GP realization-valued stochastic variable",
init_mesh_vals=None,
mesh_eval_observed=False,
trace=True,
cache_depth=2,
verbose=False):
self.conjugate = True
if not isinstance(mesh, np.ndarray) and mesh is not None:
raise ValueError, name + ": __init__ argument 'mesh' must be ndarray."
self.mesh = regularize_array(mesh)
# Safety
if isinstance(M, pm.Deterministic):
if not isinstance(M.value, Mean):
raise ValueError, 'GP' + self.__name__ + ': Argument M must be Mean instance '+\
'or pm.Deterministic valued as Mean instance, got pm.Deterministic valued as ' + M.__class__.__name__
elif not isinstance(M, Mean):
raise ValueError, 'GP' + self.__name__ + ': Argument M must be Mean instance '+\
'or pm.Deterministic valued as Mean instance, got ' + M.__class__.__name__
if isinstance(C, pm.Deterministic):
if not isinstance(C.value, Covariance):
raise ValueError, 'GP' + self.__name__ + ': Argument C must be Covariance instance '+\
'or pm.Deterministic valued as Covariance instance, got pm.Deterministic valued as ' + C.__class__.__name__
elif not isinstance(C, Covariance):
raise ValueError, 'GP' + self.__name__ + ': Argument C must be Covariance instance '+\
'or pm.Deterministic valued as Covariance instance, got ' + C.__class__.__name__
# This function will be used to draw values for self conditional on self's parents.
def random_fun(M, C):
return Realization(M, C)
self._random = random_fun
if self.mesh is not None:
self.mesh = regularize_array(self.mesh)
@pm.deterministic(verbose=verbose - 1,
cache_depth=cache_depth,
trace=False)
def M_mesh(M=M, mesh=self.mesh):
"""
The mean function evaluated on the mesh,
cached for speed.
"""
return M(mesh, regularize=False)
M_mesh.__name__ = name + '_M_mesh'
@pm.deterministic(verbose=verbose - 1,
cache_depth=cache_depth,
trace=False)
def C_and_U_mesh(C=C, mesh=self.mesh):
"""
The upper-triangular Cholesky factor of the
covariance function evaluated on the mesh,
cached for speed.
"""
# TODO: Will need to change this when sparse covariances
# are available. dpotrf doesn't know about sparse covariances.
C_old = C
C = copy.copy(C)
# Most covariances generate U_mesh automatically when observed,
# and after observation they can be used to efficiently construct realizations.
try:
junk1, junk2, U = C.observe(mesh,
np.zeros(mesh.shape[0]),
assume_full_rank=True)
except np.linalg.LinAlgError:
return np.linalg.LinAlgError
# Handle BasisCovariances separately
if U is None:
try:
U = np.linalg.cholesky(
C_old(mesh, mesh, regularize=False)).T
except np.linalg.LinAlgError:
return np.linalg.LinAlgError
# print U.T*U - C_old(mesh,mesh,regularize=False)
if U.shape[0] < U.shape[1]:
return np.linalg.LinAlgError
return U, C
C_and_U_mesh.__name__ = name + 'C_and_U_mesh'
self.M_mesh = M_mesh
self.C_and_U_mesh = C_and_U_mesh
def logp_fun(value, M, C):
if self.mesh is None:
if self.verbose > 1:
print '\t%s: No mesh, returning 0.' % self.__name__
return 0.
elif self.C_and_U_mesh.value is np.linalg.LinAlgError:
if self.verbose > 1:
print '\t%s: Covariance not positive definite on mesh, returning -infinity.' % self.__name__
return -np.Inf
else:
if self.verbose > 1:
print '\t%s: Computing log-probability.' % self.__name__
return linalg_utils.gp_array_logp(value(self.mesh),
self.M_mesh.value,
self.C_and_U_mesh.value[0])
@pm.deterministic(verbose=verbose - 1,
cache_depth=cache_depth,
trace=False)
def init_val(M=M,
C=C,
init_mesh=self.mesh,
init_mesh_vals=init_mesh_vals):
if init_mesh_vals is not None:
return Realization(M,
C,
init_mesh,
init_mesh_vals.ravel(),
regularize=False)
else:
return Realization(M, C)
init_val.__name__ = name + '_init_val'
pm.Stochastic.__init__(self,
logp=logp_fun,
doc=doc,
name=name,
parents={
'M': M,
'C': C
},
random=random_fun,
trace=trace,
value=init_val.value,
observed=False,
cache_depth=cache_depth,
verbose=verbose)