def convert_hdf_to_visibility(f): """ Convert HDF root to visibility :param f: :return: """ assert f.attrs['ARL_data_model'] == "Visibility", "Not a Visibility" s = f.attrs['phasecentre_coords'].split() ss = [float(s[0]), float(s[1])] * u.deg phasecentre = SkyCoord(ra=ss[0], dec=ss[1], frame=f.attrs['phasecentre_frame']) polarisation_frame = PolarisationFrame(f.attrs['polarisation_frame']) data = numpy.array(f['data']) vis = Visibility(data=data, polarisation_frame=polarisation_frame, phasecentre=phasecentre) vis.configuration = convert_configuration_from_hdf(f) return vis
def create_visibility(config: Configuration, times: numpy.array, frequency: numpy.array, channel_bandwidth, phasecentre: SkyCoord, weight: float, polarisation_frame=PolarisationFrame('stokesI'), integration_time=1.0, zerow=False) -> Visibility: """ Create a Visibility from Configuration, hour angles, and direction of source Note that we keep track of the integration time for BDA purposes :param config: Configuration of antennas :param times: hour angles in radians :param frequency: frequencies (Hz] [nchan] :param weight: weight of a single sample :param phasecentre: phasecentre of observation :param channel_bandwidth: channel bandwidths: (Hz] [nchan] :param integration_time: Integration time ('auto' or value in s) :param polarisation_frame: PolarisationFrame('stokesI') :return: Visibility """ assert phasecentre is not None, "Must specify phase centre" if polarisation_frame is None: polarisation_frame = correlate_polarisation(config.receptor_frame) nch = len(frequency) ants_xyz = config.data['xyz'] nants = len(config.data['names']) nbaselines = int(nants * (nants - 1) / 2) ntimes = len(times) npol = polarisation_frame.npol nrows = nbaselines * ntimes * nch nrowsperintegration = nbaselines * nch row = 0 rvis = numpy.zeros([nrows, npol], dtype='complex') rweight = weight * numpy.ones([nrows, npol]) rtimes = numpy.zeros([nrows]) rfrequency = numpy.zeros([nrows]) rchannel_bandwidth = numpy.zeros([nrows]) rantenna1 = numpy.zeros([nrows], dtype='int') rantenna2 = numpy.zeros([nrows], dtype='int') ruvw = numpy.zeros([nrows, 3]) # Do each hour angle in turn for iha, ha in enumerate(times): # Calculate the positions of the antennas as seen for this hour angle # and declination ant_pos = xyz_to_uvw(ants_xyz, ha, phasecentre.dec.rad) rtimes[row:row + nrowsperintegration] = ha * 43200.0 / numpy.pi # Loop over all pairs of antennas. Note that a2>a1 for a1 in range(nants): for a2 in range(a1 + 1, nants): rantenna1[row:row + nch] = a1 rantenna2[row:row + nch] = a2 # Loop over all frequencies and polarisations for ch in range(nch): # noinspection PyUnresolvedReferences k = frequency[ch] / constants.c.value ruvw[row, :] = (ant_pos[a2, :] - ant_pos[a1, :]) * k rfrequency[row] = frequency[ch] rchannel_bandwidth[row] = channel_bandwidth[ch] row += 1 if zerow: ruvw[..., 2] = 0.0 assert row == nrows rintegration_time = numpy.full_like(rtimes, integration_time) vis = Visibility(uvw=ruvw, time=rtimes, antenna1=rantenna1, antenna2=rantenna2, frequency=rfrequency, vis=rvis, weight=rweight, imaging_weight=rweight, integration_time=rintegration_time, channel_bandwidth=rchannel_bandwidth, polarisation_frame=polarisation_frame) vis.phasecentre = phasecentre vis.configuration = config log.info("create_visibility: %s" % (vis_summary(vis))) assert isinstance(vis, Visibility), "vis is not a Visibility: %r" % vis return vis