"""
This module contains classes for defining gradients operators. Taken from
pysap-mri with minor changes (name of parameters (data_op), change of data
type to float).
"""
import numpy as np
from modopt.math.matrix import PowerMethod
from modopt.opt.gradient import GradBasic
[docs]class GradAnalysis(GradBasic, PowerMethod):
"""
Gradient operator for the data attachment term in the reconstruction
process in analysis formulation
"""
def __init__(self, data_op):
GradBasic.__init__(self, np.array(0), data_op.op, data_op.adj_op)
self.data_op = data_op
PowerMethod.__init__(self, self.trans_op_op, self.data_op.shape,
data_type=data_op.dtype, auto_run=False)
self.get_spec_rad(extra_factor=1.1)
[docs]class GradSynthesis(GradBasic, PowerMethod):
"""
Gradient operator for the data attachment term in the reconstruction
process in synthesis formulation
"""
def __init__(self, linear_op, data_op):
GradBasic.__init__(self, np.array(0), self._op_method,
self._trans_op_method)
self.data_op = data_op
self.linear_op = linear_op
coef = linear_op.op(np.zeros(data_op.shape).astype(data_op.dtype))
PowerMethod.__init__(self, self.trans_op_op, coef.shape,
data_type=data_op.dtype, auto_run=False)
self.get_spec_rad(extra_factor=1.1)
[docs] def _op_method(self, data, *args, **kwargs):
# pylint: disable=unused-argument
return self.data_op.op(self.linear_op.adj_op(data))
[docs] def _trans_op_method(self, data, *args, **kwargs):
# pylint: disable=unused-argument
return self.linear_op.op(self.data_op.adj_op(data))
