def series_nfft(series,
oversample=4):
"""
note that output period units are [days] (so is frequency)
"""
M = len(series)
if not is_power_of_2(M):
raise ValueError('series length {} is not a power of 2'.format(len(series)))
N = M
if N % 2 == 1:
# number of frequency samples must be even
N += 1
N *= oversample
# re-grid time the interval [-1/2, 1/2) as required by nfft
time = series.index.astype(NP.int64) / 1e9
time -= time[0]
b = -0.5
a = (M - 1) / (M * time[-1])
x = a * time + b
# setup for nfft computation
plan = NFFT(N, M)
plan.x = x
plan.f = series.values
plan.precompute()
# compute nfft (note that conjugation is necessary because of the
# difference in transform sign convention)
x_nfft = NP.conj(plan.adjoint())
# calculate frequencies and periods
dt = ((series.index[-1] - series.index[0]) / M).total_seconds() / DAYS_TO_SECONDS
f_range = NP.fft.fftshift(NP.fft.fftfreq(N, dt))
T_range = 1 / f_range
return x_nfft, f_range, T_range
def autocorrelation_dfft(times, trajs):
"""
This function never worked... need to download correct packages
"""
# for now do the first trajectory
nodes = times; values = trajs[0]
from pynfft import NFFT, Solver
M = len(times)
N = 128
f = np.empty(M, dtype=np.complex128)
f_hat = np.empty([N,N], dtype=np.complex128)
this_nfft = NFFT(N=[N,N], M=M)
this_nfft.x = np.array([[node_i,0.] for node_i in nodes])
this_nfft.precompute()
this_nfft.f = f
ret2=this_nfft.adjoint()
#print this_nfft.x # nodes in [-0.5, 0.5), float typed
this_solver = Solver(this_nfft)
this_solver.y = values # '''right hand side, samples.'''
#this_solver.f_hat_iter = f_hat # assign arbitrary init sol guess, default 0
this_solver.before_loop() # initialize solver internals
while not np.all(this_solver.r_iter < 1e-2):
this_solver.loop_one_step()
# plotting
fig=plt.figure(1,(20,5))
ax =fig.add_subplot(111)
foo=[ np.abs( this_solver.f_hat_iter[i][0])**2\
for i in range(len(this_solver.f_hat_iter) ) ]
ax.plot( np.abs(np.arange(-N/2,+N/2,1)) )
plt.show()
return autocor, spectrum
def fourier(event, fit, fignum, savefile):
x = fit.timeunit
y = fit.residuals
shift1 = x[0]
newx = x - shift1
stretch1 = 1 / x[-1]
newx *= stretch1
shift2 = 0.5
newx -= shift2
M = len(y)
N = M // 2
nfft_obj = NFFT(N, M=M)
nfft_obj.x = newx
nfft_obj.precompute()
nfft_obj.f = y
nfft_obj.adjoint()
power = np.zeros(len(nfft_obj.f_hat))
for i in range(len(nfft_obj.f_hat)):
power[i] = np.abs(nfft_obj.f_hat[i])**2
k = np.arange(-N // 2, N // 2, 1)
plt.clf()
plt.plot(k, power)
plt.xlabel('Frequency (periods/dataset)')
plt.ylabel('Power')
plt.title('Power spectrum of Fourier transform of residuals')
plt.xlim((0, M // 500))
#plt.ylim((0,max(power[N/2:N/2+M/500])))
if savefile != None:
plt.savefig(savefile)
return
def singleFrequency():
imsize = (256, 256)
cell = np.asarray(
[0.5, -0.5]
) / 3600.0 # #arcseconds. revert v axis because it is empirically right. the axes in the ms are not really standardized
cell = np.radians(cell)
ms = MS_jon()
ms.read_ms("simkat64-default.ms")
# 4 polarizations are XX, XY, YX and YY
#Intensity image should be XX + YY
wavelengths = ms.freq_array[0, 0] / constants.c
uvw_wavelengths = np.dot(ms.uvw_array, np.diag(np.repeat(wavelengths, 3)))
uv = np.multiply(uvw_wavelengths[:, 0:2], cell)
plan = NFFT(imsize, uv.shape[0])
plan.x = uv.flatten()
plan.precompute()
plan.f = ms.data_array[:, :, 0, 0]
dirty = plan.adjoint() / uv.shape[0]
plt.imshow(np.flipud(np.transpose(np.real(dirty))))
def allFrequencies():
imsize = (256, 256)
cell = np.asarray(
[0.5, -0.5]
) / 3600.0 # #arcseconds. revert v axis because it is empirically right. the axes in the ms are not really standardized
cell = np.radians(cell)
ms = MS_jon()
ms.read_ms("simkat64-default.ms")
wavelengths = ms.freq_array[0] / constants.c
offset = ms.uvw_array.shape[0]
start = 0
end = offset
uv = np.zeros((ms.uvw_array.shape[0] * wavelengths.size, 2))
vis = np.zeros(ms.uvw_array.shape[0] * wavelengths.size,
dtype=np.complex128)
for i in range(0, wavelengths.size):
uvw_wavelengths = np.dot(ms.uvw_array,
np.diag(np.repeat(wavelengths[i], 3)))
#skip w component
uv[start:end] = uvw_wavelengths[:, 0:2]
#add the XX and YY Polarization to get an intensity
vis[start:end] = ms.data_array[:, 0, i, 0] + ms.data_array[:, 0, i, 3]
start += offset
end += offset
uv = np.multiply(uv, cell)
plan = NFFT(imsize, uv.shape[0])
plan.x = uv.flatten()
plan.precompute()
plan.f = vis
dirty = plan.adjoint() / uv.shape[0] / 2
plt.imshow(np.real(dirty))
print(np.max(np.real(dirty)))
return 0
sio.loadmat("/home/jon/Desktop/export_mat/dirty.mat")["dirty"])
#p_shaped = np.reshape( (1/6.0)*p, (p.shape[0]*p.shape[1]))
#dim= (1024,1024)
p_shaped = np.reshape((1 / 4.0) * p, (p.shape[0] * p.shape[1]))
dim = (256, 256)
plan = NFFT(dim, y.size)
plan.x = p_shaped
plan.precompute()
infft = Solver(plan)
infft.w = np.ones(y.shape)
infft.y = y
infft.f_hat_iter = np.zeros(dim, dtype=np.complex128)
infft.before_loop()
niter = 100 # set number of iterations to 10
for iiter in range(niter):
print("alive" + str(iiter))
print(np.max(infft.r_iter))
infft.loop_one_step()
if (np.all(infft.r_iter < 0.001)):
break
res = infft.f_hat_iter
plt.imshow(np.real(res))
plan.f = y
res_adjoint = plan.adjoint()
u1 = (-cell)*(71.50 / wave_length) v1 = (cell)*(-368.67 / wave_length) vis1 = toComplex(53.456, math.radians(162.4)+2*math.pi*(u1*27+v1*27)) vis1 = toComplex(53.456, math.radians(173.2)) dim = [54,54] img = np.zeros(dim, dtype=np.complex128) inverseFT(img, vis0, u0, v0) inverseFT(img, vis1, u1, v1) #inverseFT(img, 1, 0.2,1) plt.imshow(np.real(img)) print(img[0,0]) . plan = NFFT(dim, 2) plan.x = np.asarray([u0, v0, u1, v1]) plan.precompute() plan.f = np.asarray([vis0, vis1]) res = plan.adjoint(use_dft=True) print(res[0,0]) plt.imshow(np.real(res))
#print "Number of values: ", len(values)
#sys.exit(0)
# Fourier transform: initialization and precompute
M = len(nodes) # number of nodes
N = len(nodes) # number of Fourier coefficients
f = np.empty(M, dtype=np.complex128)
f_hat = np.empty([N, N], dtype=np.complex128)
this_nfft = NFFT(N=[N, N], M=M)
this_nfft.x = np.array([[node_i, 0.] for node_i in nodes])
this_nfft.precompute()
#print "precompute done"
this_nfft.f = f
ret2 = this_nfft.adjoint()
#print "adjoint done"
#print this_nfft.M # number of nodes, complex typed
#print this_nfft.N # number of Fourier coefficients, complex typed
#print this_nfft.x # nodes in [-0.5, 0.5), float typed
this_solver = Solver(this_nfft)
#print "Solver initialized"
this_solver.y = values # '''right hand side, samples.'''
#print "y-values defined"
"""if iPoisson == 0:
this_solver.f_hat_iter = f_hat # assign 0 as initial solution guess, if it's the first Poisson realization
else:
this_solver.f_hat_iter = f_hat_guess # assign Fourier transform of previous Poisson iteration otherwise"""
