casa6

import collections

import glob

import itertools

import numpy

import os

​

try:

    from casatools import msmetadata

    from casatools import table

    from casatools import measures

    from casatools import quanta

    from casatools import ms as mstool

    from casatools import image

    from casatasks import casalog

except Exception:

    from __casac__.msmetadata import msmetadata

    from __casac__.table import table

    from __casac__.measures import measures

    from __casac__.quanta import quanta

    from __casac__.ms import ms as mstool

    from __casac__.image import image

    from taskinit import casalog

​

MetaDataSet = collections.namedtuple(

    'MetaDataSet',

    ['msmeta', 'ephemmeta']

)

​

MsMeta = collections.namedtuple(

    'MsMeta',

    ['positions', 'times', 'freqmin', 'freqmax']

)

​

EphemMeta = collections.namedtuple(

    'EphemMeta',

    ['table', 'times', 'unit_time', 'velocities', 'unit_vel', 'frame_vel']

)

​

FrequencyRange = collections.namedtuple(

    'FrequencyRange',

    ['min', 'max', 'ref']

)

​

COMMON_VELOCITY_UNIT = 'km/s'

​

DEBUG = False

​

​

def debug_print(msg):

    if DEBUG:

        for m in msg.split('\n'):

            casalog.post('DEBUG: {}'.format(m))

​

​

def inspect_ms(vis, fieldid, spwid, chanstart=0, nchan=-1):

    """Inspect MS

​

    Arguments:

        vis {str} -- name of MS

        fieldid {int} -- FIELD_ID for target

        spwid {int} -- SPW_ID for target spw

        chanstart {int} -- start channel (default: 0)

        nchan {int} -- number of channels

                       (default: -1 => from chanstart to end channel of spw)

​

    Returns:

        MsMeta -- namedtuple containing metadata

                      positions: list of antenna positions

                      times: list of timestamps for target field

                      freqmin: minimum frequency of given spw as measure

                      freqmax: maximum frequency of given spw as measure

    """

    msmd = msmetadata()

    msmd.open(vis)

    try:

        positions = list(map(msmd.antennaposition, msmd.antennaids()))

        chanfreqs = msmd.chanfreqs(spwid)

        chanwidths = msmd.chanwidths(spwid)

    finally:

        msmd.close()

​

    cw = chanwidths.mean()

    start = chanstart

    end = min(chanstart + nchan, len(chanfreqs)) if nchan >= 0 else len(chanfreqs)

    debug_print('start {}, end {}'.format(start, end))

    assert 0 <= start

    assert 0 < end

    assert start < end

    freqmin = chanfreqs[start:end].min() - cw / 2

    freqmax = chanfreqs[start:end].max() + cw / 2

    debug_print('freqmin {}, freqmax {}'.format(freqmin, freqmax))