Commit 8ec6d1f7 authored by Philipp Arras's avatar Philipp Arras

Add gridder maker

parent 53c0d64a
Pipeline #46601 passed with stages
in 8 minutes and 25 seconds
......@@ -87,6 +87,7 @@ from .library.correlated_fields import CorrelatedField, MfCorrelatedField
from .library.adjust_variances import (make_adjust_variances_hamiltonian,
do_adjust_variances)
from .library.nfft import NFFT
from .library.gridder import GridderMaker
from . import extra
......
import numpy as np
from ..domain_tuple import DomainTuple
from ..domains.rg_space import RGSpace
from ..domains.unstructured_domain import UnstructuredDomain
from ..fft import fftn, ifftn
from ..operators.linear_operator import LinearOperator
from ..sugar import from_global_data, makeDomain
class GridderMaker(object):
def __init__(self, domain, eps=1e-15):
domain = makeDomain(domain)
if (len(domain) != 1 or not isinstance(domain[0], RGSpace) or
not len(domain.shape) == 2):
raise ValueError("need domain with exactly one 2D RGSpace")
nu, nv = domain.shape
if nu % 2 != 0 or nv % 2 != 0:
raise ValueError("dimensions must be even")
rat = 3 if eps < 1e-11 else 2
nu2, nv2 = rat*nu, rat*nv
nspread = int(-np.log(eps)/(np.pi*(rat-1)/(rat-.5)) + .5) + 1
nu2 = max([nu2, 2*nspread])
nv2 = max([nv2, 2*nspread])
r2lamb = rat*rat*nspread/(rat*(rat-.5))
oversampled_domain = RGSpace(
[nu2, nv2], distances=[1, 1], harmonic=False)
self._nspread = nspread
self._r2lamb = r2lamb
self._rest = _RestOperator(domain, oversampled_domain, r2lamb)
def getReordering(self, uv):
from testgridder import peanoindex
nu2, nv2 = self._rest._domain.shape
return peanoindex(uv, nu2, nv2)
def getGridder(self, uv):
return RadioGridder(self._rest.domain, self._nspread, self._r2lamb, uv)
def getRest(self):
return self._rest
def getFull(self, uv):
return self.getRest() @ self.getGridder(uv)
class _RestOperator(LinearOperator):
def __init__(self, domain, oversampled_domain, r2lamb):
self._domain = makeDomain(oversampled_domain)
self._target = domain
nu, nv = domain.shape
nu2, nv2 = oversampled_domain.shape
# compute deconvolution operator
rng = np.arange(nu)
k = np.minimum(rng, nu-rng)
c = np.pi*r2lamb/nu2**2
self._deconv_u = np.roll(np.exp(c*k**2), -nu//2).reshape((-1, 1))
rng = np.arange(nv)
k = np.minimum(rng, nv-rng)
c = np.pi*r2lamb/nv2**2
self._deconv_v = np.roll(np.exp(c*k**2)/r2lamb, -nv//2).reshape((1, -1))
self._capability = self.TIMES | self.ADJOINT_TIMES
def apply(self, x, mode):
self._check_input(x, mode)
nu, nv = self._target.shape
res = x.to_global_data_rw()
if mode == self.TIMES:
res = ifftn(res)*res.size
res = np.roll(res, (nu//2, nv//2), axis=(0, 1))
res = res[:nu, :nv]
res *= self._deconv_u
res *= self._deconv_v
else:
res *= self._deconv_u
res *= self._deconv_v
nu2, nv2 = self._domain.shape
res = np.pad(res, ((0, nu2-nu), (0, nv2-nv)), 'constant',
constant_values=0)
res = np.roll(res, (-nu//2, -nv//2), axis=(0, 1))
res = fftn(res)
return from_global_data(self._tgt(mode), res)
class RadioGridder(LinearOperator):
def __init__(self, target, nspread, r2lamb, uv):
self._domain = DomainTuple.make(
UnstructuredDomain((uv.shape[0],)))
self._target = DomainTuple.make(target)
self._capability = self.TIMES | self.ADJOINT_TIMES
self._nspread, self._r2lamb = int(nspread), float(r2lamb)
self._uv = uv # FIXME: should we write-protect this?
def apply(self, x, mode):
from testgridder import to_grid, from_grid
self._check_input(x, mode)
nu2, nv2 = self._target.shape
x = x.to_global_data()
if mode == self.TIMES:
res = to_grid(self._uv, x, nu2, nv2, self._nspread,
self._r2lamb)
else:
res = from_grid(self._uv, x, nu2, nv2, self._nspread,
self._r2lamb)
return from_global_data(self._tgt(mode), res)
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