def get_alms_iso(events, l_max):
cplx_alms = np.zeros(Alm.getsize(l_max), dtype=complex)
for l in xrange(l_max + 1):
for m in xrange(l + 1):
cplx_alms[Alm.getidx(l_max, l, m)] = np.mean(
cplxYlm(l, m, events["theta"], events["phi"]))
return cplx_alms
def real2cplx_alms(real_alms):
"""
convert denton's real alms to healpy's complex alms
"""
l_max = np.sqrt(len(real_alms)) - 1
assert l_max == int(l_max)
l_max = int(l_max)
cplx_alms = np.zeros(Alm.getsize(l_max), dtype=complex)
for i in xrange(len(real_alms)):
l, m = i2lm(i)
if m == 0:
cplx_alms[Alm.getidx(l_max, l, m)] = real_alms[i]
if m < 0:
cplx_alms[Alm.getidx(
l_max, l, abs(m))] += -(-1)**m * 1j * real_alms[i] / np.sqrt(2)
if m > 0:
cplx_alms[Alm.getidx(l_max, l, m)] += real_alms[i] / np.sqrt(2)
return cplx_alms
def get_alms_exposure(events, l_max, ff):
# this is the prefered way
# 1702.07209 eq 8
# same as Sommers
omegas = CR.omega(events["dec"], ff)
# check field names in events
phi_field = "phi"
if phi_field not in events.dtype.names:
names = list(events.dtype.names)
idx = names.index("RA")
names[idx] = phi_field
events.dtype.names = names
exposure_alms = np.zeros(Alm.getsize(l_max), dtype=complex)
for l in xrange(l_max + 1):
for m in xrange(l + 1):
cplx_alms = cplxYlm(l, m, CR.dec2theta(events["dec"]),
events["phi"]) / omegas
exposure_alms[Alm.getidx(l_max, l, m)] = np.sum(cplx_alms)
return exposure_alms / (exposure_alms[0] * np.sqrt(4 * np.pi)
) # normalize the alms so that a00 = 1/sqrt(4pi)
def swhtProcessCorrelations(corrDict, options, processDict, xyz, stationLocation, metaDataArr, frequency, labelOptions):
"""Handler for converting an observation to a full sky map through the spherical wave harmonic transform.
Args:
corrDict (dict): Dictionary of elements in the format 'CORRELATION': (nAnts x nAnts x nSamples array of correlations)
options (dict): Standard options dictionary
processDict (dict): Dictionary of correlation times ('XX', 'XY'...) and values of whether or not to process them
xyz (np.ndarray): Antenna locations nAnts x 3
stationLocation (list): Station location in (lon (deg), lat (deg) and elevation (meters))
metaDataArr (list): List of dictionaries formatted as strings from the input dataset attributes
frequency (float): Observing frequency (in Hz)
labelOptions (list): List of useful values for plotting
Returns:
dict: Dictionary of processed outputs ('XX', 'I',....)
"""
# Borrowed from Griffith's method as an optomisisation, cuts processed values by a factor of 2.
# Should look into implementing in the FT method? After all, we can recreate the lost correlations
# by getting their complex conjugate.
xyz = xyz - xyz.transpose(1,0,2)
xyzTriu = np.triu_indices(xyz.shape[0])
xyz = xyz[xyzTriu]
# Extract the integration midpoints from the metadata array.
dateArr = [dateTime.split("'integrationMidpoint': '")[1].split("', ")[0] for dateTime in metaDataArr]
# We need to use two sets of locations: The true location for the zenith ponting and an arbitrary lon/lat for the uvw plane.
trueTelescopeLoc = astropy.coordinates.EarthLocation( lat = stationLocation[1] * u.deg, lon = stationLocation[0] * u.deg, height = stationLocation[2] * u.m )
telescopeLoc = astropy.coordinates.EarthLocation(lat = 0 * u.deg, lon = -90 * u.deg, height = 0 * u.m) # Not sure why, used by Griffin as a baseline for calculations and it works.
# Initialise the UVW array
uvw = np.zeros([0] + list(xyz.shape))
zenithArr = []
timeArr = []
for timestamp in dateArr:
# Get two sets of times: One for getting the zenith, the other for plotting the observation title times in local time
obsTime = astropy.time.Time(timestamp, scale = 'utc', location = telescopeLoc)
utcObsTime = astropy.time.Time(timestamp, scale = 'utc')
altAz = astropy.coordinates.AltAz(az = 0. * u.deg, alt = 90. * u.deg, location = trueTelescopeLoc, obstime = utcObsTime)
zenith = altAz.transform_to(astropy.coordinates.Galactic)
sidAngle = float(obsTime.sidereal_time('mean').radian)
zenithArr.append(zenith)
timeArr.append(obsTime)
# Rotate the baselines to generate a uvw-like plane (still needs to be divded by wavelength)
sinSA = np.sin(sidAngle)
cosSA = np.cos(sidAngle)
rotationMatrix = np.array([[sinSA, cosSA, 0.],
[-1. * cosSA, sinSA, 0.],
[0., 0., 1.]])
uvw = np.concatenate([uvw, np.dot(rotationMatrix, xyz.T).T[np.newaxis]], axis = 0)
print('UVW Successfully generated for timestamp {0} with zenith at {1:.2f}, {2:.2f} (GAL)'.format(timestamp[:-5], zenith.l.deg, zenith.b.deg))
# Convert the UVW coordinates to r, theta, phi (referred to as rtp) for spherical coordinates
r, theta, phi = cartToSpherical(uvw)
r = r[0] # All samples have the same r values
# Generate the k-vector to normalise the r elements
k_0 = 2. * np.pi * frequency / scipy.constants.c
preFac = 2. * (k_0 ** 2) / np.pi
kRVec = k_0 * r
# Get the maximum l value from the options dictionary and prepare the result arrays
lMax = options['imagingOptions']['swhtlMax']
arraySize = almMap.getsize(lMax - 1)
results = np.zeros(arraySize, dtype = complex)
maskVar = np.ones(healpy.nside2npix(max(64, 2 * lMax)), dtype=np.bool)
# Account for autocorrelations (remove excess np.nans from results as r = 0 causes issues to say the least)
kZeroBool = kRVec == 0.
# Generate the mask based on the pointings: pixels are masked if they are never within 90 degrees of a zenith pointing
if options['imagingOptions']['maskOutput']:
pixelTheta, pixelPhi = healpy.pix2ang(max(64, 2 * lMax), np.arange(healpy.nside2npix(max(64, 2 * lMax))), lonlat = True)
# F**k everyhting about this coordinate system...
# For further context: standard latitutde and longitude, healpy and galactic coordinates all have different
# ways of wrapping angles. I created functions to map between the different coordinate systems
pixelTheta = usefulFunctions.lonToHealpyLon(pixelTheta, rads = False)
galCoordLon = np.array([skyCoord.l.deg for skyCoord in zenithArr])
galCoordLat = np.array([skyCoord.b.deg for skyCoord in zenithArr])
# Convert to radians for easier angular maths
galCoordSampled = np.deg2rad(np.vstack([galCoordLon, galCoordLat])[:, np.newaxis])
pixelCoord = np.deg2rad(np.vstack([pixelTheta, pixelPhi])[..., np.newaxis])
# Check where the angular difference is less than 70 (ie., 35 degrees in any direction., save as used for all sky maps)
# Not sure about where the factor of 2 is coming from, but I can visually confirm that this works.
deltaLoc = greatCircleAngularDiff(galCoordSampled, pixelCoord)
maskVar = np.logical_not(np.any(np.rad2deg(deltaLoc) < 35, axis = 1))
procDict = {}
# Create a rotate to convert from arbitrary healpy logic to cartesian-galactic coordinates
galRotator = healpy.rotator.Rotator(coord = ['C','G'])
for key, value in processDict.items():
# processDict is a dictionary of keys/values of correlations and whether or not they are needed for the output images
# So if we were imaging the Stokes I, we would have {'XX': True, 'YY': True, 'XY': False,...}, making it easy to only processed
# the required correlations.
if value:
# Drop the autocorrelations; we have to remove the r = 0 elements to get rid of inf/nans
corrDict[key][np.eye(corrDict[key].shape[0], dtype = bool)] = 0.
inputDropped = corrDict[key][xyzTriu]
# Multithreaded, might not be more efficient if I implement Schaeffer 2015
if options['multiprocessing']:
processCount = int(mp.cpu_count()-1)
mpPool = mp.Pool(processes = processCount)
fragments = [np.arange(lMax)[i::processCount] for i in range(processCount)]
callBacks = [mpPool.apply_async(swhtWorker.swhtWorker, args = ([idx, fragmentChunk, lMax, kRVec, kZeroBool, inputDropped, phi, theta, preFac, results, uvw])) for idx, fragmentChunk in enumerate(fragments)]
mpPool.close()
mpPool.join()
for asyncResult in callBacks:
idx, resultsVar = asyncResult.get()
results[resultsVar != 0.] = resultsVar[resultsVar != 0.]
allSkyImageAlm = results
else:
allSkyImageAlm = swhtWorker.swhtWorker(0, lMax, lMax, kRVec, kZeroBool, inputDropped, phi, theta, preFac, results, uvw)[1]
# Convert the results to a healpy map
procDict['{0}-alm'.format(key)] = allSkyImageAlm
hpMap = healpy.alm2map(allSkyImageAlm, max(64, 2 * lMax)).astype(complex)
# Clone + generate imaginary map as well (as healpy seems to hate imaginary values results)
# Not sure if this is the right way to go about doing things, but it seems to function at least.
# Can't find a Stokes-V map of the sky to compare.
clone = allSkyImageAlm.copy()
clone.real = clone.imag
clone.imag = np.zeros_like(allSkyImageAlm)
hpMap.imag = healpy.alm2map(clone, max(64, 2 * lMax))
# Rotate to the right coordinate system
hpMap = galRotator.rotate_map(hpMap)
# Store the results]
print("{0} Polarisation Processed.".format(key))
procDict[key] = hpMap
# Process each of the requested outputs
for method in options['imagingOptions']['correlationTypes']:
if len(method) == 2:
allSkyImage = procDict[method].real
allSkySave = procDict[method]
elif 'I' is method:
allSkySave = (procDict['XX'] + procDict['YY'])
allSkyImage = allSkySave.real
elif 'Q' is method:
allSkySave = (procDict['XX'] - procDict['YY'])
allSkyImage = allSkySave.real
elif 'U' is method:
allSkySave = (procDict['XY'] + procDict['YX'])
allSkyImage = allSkySave.real
elif 'V' is method:
# Healpy doesn't like dealing with imaginary values, take the 'V' output with a mountain of salt.
allSkySave = (procDict['YX'] - procDict['XY'])
allSkyImage = allSkySave.imag
else:
print('How did we get this far with a broken method \'{0}\'? Processing the first value in procDict so it hasn\'t gone to waste...'.format(method))
allSkyImage = procDict.values()[0]
method = procDict.keys()[0]
# Mask off values if needed.
# For note, doing it before this point breaks stuff as the masked arrays fail to mask on simple maths (values on the other of 1e40 anyone?)
allSkyImage = healpy.ma(allSkyImage)
allSkySave = healpy.ma(allSkySave)
allSkyImage.mask = maskVar
allSkySave.mask = maskVar
# Don't save the result out of we are doing a pure-correlation map
procDict[method] = allSkySave
if options['plottingOptions']['plotImages']:
swhtPlot(allSkyImage, options, labelOptions + [method, 0], healpy.newvisufunc.mollview, [timeArr, trueTelescopeLoc], zenithArr, metaDataArr)
# Save a copy of the mask encase it gets mangled again.
procDict['mask'] = maskVar
return procDict
def get_alms_iso_exact(l_max):
assert l_max == int(l_max)
return np.zeros(Alm.getsize(l_max), dtype=complex)
def lmax(self, l):
self._almsize = Alm.getsize(l - 1)
self._hpsize = max(128, 2 * l) #max(64, 2 * l)
self._max = l
return