def _tau_to_kappa(tau):
"""Using non-linear optimization, convert the NODDI-DTI Tau variables to NODDI kappa's.
Args:
tau (ndarray): the list of tau's per voxel.
Returns:
ndarray: the list of corresponding kappa's
"""
tau_func = SimpleCLFunction.from_string('''
double tau(double kappa){
if(kappa < 1e-12){
return 1/3.0;
}
return 0.5 * ( 1 / ( sqrt(kappa) * dawson(sqrt(kappa) ) ) - 1/kappa);
}''',
dependencies=[dawson()])
objective_func = SimpleCLFunction.from_string('''
double tau_to_kappa(local const mot_float_type* const x, void* data, local mot_float_type* objective_list){
return pown(tau(x[0]) - ((_tau_to_kappa_data*)data)->tau, 2);
}
''',
dependencies=[tau_func])
kappa = minimize(objective_func,
np.ones_like(tau),
data=Struct(
{'tau': Array(tau, 'mot_float_type', as_scalar=True)},
'_tau_to_kappa_data')).x
kappa[kappa > 64] = 1
kappa[kappa < 0] = 1
return kappa
def _single_optimization_run(self, y_star, x0, roi_indices):
"""Generate one new sample using a single run of the optimization routine."""
self._roi_input_data.observations[roi_indices] = y_star
self._model.set_input_data(self._roi_input_data,
suppress_warnings=True)
kernel_data_subset = self._model.get_kernel_data().get_subset(
roi_indices)
results = minimize(
self._objective_func,
x0,
method=self._optimization_method,
nmr_observations=self._model.get_nmr_observations(),
cl_runtime_info=self._cl_runtime_info,
data=self._wrapper.wrap_input_data(kernel_data_subset),
lower_bounds=self._get_bounds(self._lower_bounds, roi_indices),
upper_bounds=self._get_bounds(self._upper_bounds, roi_indices),
constraints_func=self._constraints_func,
options=self._optimizer_options)
x_final_array = self._codec.decode(results['x'], kernel_data_subset)
x_dict = split_array_to_dict(x_final_array,
self._model.get_free_param_names())
x_dict.update(
self._model.get_post_optimization_output(x_final_array,
roi_indices=roi_indices,
parameters_dict=x_dict))
return x_dict
def _tau_to_kappa(tau):
"""Using non-linear optimization, convert the NODDI-DTI Tau variables to NODDI kappa's.
Args:
tau (ndarray): the list of tau's per voxel.
Returns:
ndarray: the list of corresponding kappa's
"""
tau_func = SimpleCLFunction.from_string('''
mot_float_type tau(mot_float_type kappa){
if(kappa < 1e-12){
return 1/3.0;
}
return 0.5 * ( 1 / ( sqrt(kappa) * dawson(sqrt(kappa) ) ) - 1/kappa);
}''',
dependencies=[dawson()])
objective_func = SimpleCLFunction.from_string('''
double tau_to_kappa(local const mot_float_type* const x, void* data, local mot_float_type* objective_list){
return pown(tau(x[0]) - *((mot_float_type*)data), 2);
}
''',
dependencies=[tau_func])
kappa = minimize(objective_func,
np.ones_like(tau),
data=Array(tau, 'mot_float_type')).x
return np.clip(kappa, 0, 64)
def test_model(self):
for method in self.methods:
output = minimize(self._objective_func, np.array([[0.3, 0.4]]), method=method,
nmr_observations=self._nmr_observations)
v = output['x']
for ind in range(2):
self.assertAlmostEqual(v[0, ind], 0.2578, places=3, msg=method)
def test_model(self):
for method, options in self.methods.items():
output = minimize(self._objective_func, np.array([[3] * 5]), method=method,
nmr_observations=self._nmr_observations, options=options)
v = output['x']
for ind in range(2):
self.assertAlmostEqual(v[0, ind], 1, places=3, msg=method)
def _reconstruct_slice(self, slice_data, slice_index):
nmr_timeseries = slice_data.shape[-2]
nmr_channels = slice_data.shape[-1]
batch = np.reshape(slice_data, (-1, nmr_timeseries, nmr_channels))
codec = STARCOptimizationCodec(nmr_channels)
data = Struct({'observations': Array(batch.reshape((batch.shape[0], -1))),
'scratch': LocalMemory('double', nmr_items=batch.shape[1] + 4)},
'starc_data')
wrapper = ParameterDecodingWrapper(nmr_channels)
result = minimize(wrapper.wrap_objective_function(get_starc_objective_func(batch), codec.get_decode_function()),
codec.encode(self._get_starting_weights(slice_index, batch)),
data=wrapper.wrap_input_data(data),
cl_runtime_info=self.cl_runtime_info)
weights = codec.decode(result['x'])
reconstruction = np.sum(batch * weights[:, None, :], axis=2)
sos = np.sqrt(np.sum(np.abs(slice_data).astype(np.float64) ** 2, axis=-1))
reconstruction = np.reshape(reconstruction, slice_data.shape[:-2] + (nmr_timeseries,))
reconstruction *= (np.mean(sos, axis=2) / np.mean(reconstruction, axis=2))[:, :, None]
return {
'weights': np.reshape(weights, slice_data.shape[:-2] + (nmr_channels,)),
'reconstruction': reconstruction,
}
def _process(self, roi_indices, next_indices=None):
self._logger.info('Starting optimization')
self._logger.info('Using MOT version {}'.format(mot.__version__))
self._logger.info(
'We will use a {} precision float type for the calculations.'.
format('double' if self._cl_runtime_info.
double_precision else 'single'))
for env in self._cl_runtime_info.cl_environments:
self._logger.info('Using device \'{}\'.'.format(str(env)))
self._logger.info('Using compile flags: {}'.format(
self._cl_runtime_info.compile_flags))
if self._optimizer_options:
self._logger.info('We will use the optimizer {} '
'with optimizer settings {}'.format(
self._method, self._optimizer_options))
else:
self._logger.info(
'We will use the optimizer {} with default settings.'.format(
self._method))
kernel_data_subset = self._kernel_data.get_subset(roi_indices)
x0 = self._codec.encode(self._initial_params[roi_indices],
kernel_data_subset)
results = minimize(
self._objective_func,
x0,
method=self._method,
nmr_observations=self._model.get_nmr_observations(),
cl_runtime_info=self._cl_runtime_info,
data=self._wrapper.wrap_input_data(kernel_data_subset),
lower_bounds=self._get_bounds(self._lower_bounds, roi_indices),
upper_bounds=self._get_bounds(self._upper_bounds, roi_indices),
constraints_func=self._constraints_func,
options=self._optimizer_options)
self._logger.info('Finished optimization')
self._logger.info('Starting post-processing')
x_final_array = self._codec.decode(results['x'], kernel_data_subset)
x_dict = split_array_to_dict(x_final_array,
self._model.get_free_param_names())
x_dict.update({'ReturnCodes': results['status']})
x_dict.update(
self._model.get_post_optimization_output(x_final_array,
roi_indices=roi_indices,
parameters_dict=x_dict))
x_dict.update({
self._used_mask_name:
np.ones(roi_indices.shape[0], dtype=np.bool)
})
self._logger.info('Finished post-processing')
self._write_output_recursive(x_dict, roi_indices)