Utilities¶

Some utilities useful internally and externally from ragavi

ragavi.utils.calc_amplitude(ydata)¶

Convert complex data to amplitude (absolute value)

Parameters:	ydata (`xarray.DataArray`) – y axis data to be processed
Returns:	amplitude (`xarray.DataArray`) – `ydata` converted to an amplitude

ragavi.utils.calc_imaginary(ydata)¶

Extract imaginary part from complex data

Parameters:	ydata (`xarray.DataArray`) – y-axis data to be processed
Returns:	imag (`xarray.DataArray`) – Imaginary part of `ydata`

ragavi.utils.calc_phase(ydata, unwrap=False)¶

Convert complex data to angle in degrees

Parameters:	wrap (`bool`) – whether to wrap angles between 0 and 2pi ydata (`xarray.DataArray`) – y-axis data to be processed
Returns:	phase (xarray.DataArray) – `ydata` data converted to degrees

ragavi.utils.calc_real(ydata)¶

Extract real part from complex data

Parameters:	ydata (`xarray.DataArray`) – y-axis data to be processed
Returns:	real (`xarray.DataArray`) – Real part of `ydata`

ragavi.utils.calc_unique_bls(n_ants=None)¶

Calculate number of unique baselines :param n_ants: Available antennas :type n_ants: int

Returns:	pq (`int`) – Number of unique baselines

ragavi.utils.calc_uvdist(uvw)¶

Calculate uv distance in metres

Parameters:	uvw (`xarray.DataArray`) – UVW column from measurement set
Returns:	uvdist (`xarray.DataArray`) – uv distance in meters

ragavi.utils.calc_uvwave(uvw, freq)¶

Calculate uv distance in wavelength for availed frequency. This function also calculates the corresponding wavelength. Uses output from ragavi.vis_utils.calc_uvdist()

Parameters:	freq (xarray.DataArray or :obj:`float) – Frequency(ies) from which corresponding wavelength will be obtained. uvw (`xarray.DataArray`) – UVW column from the MS dataset
Returns:	uvwave (`xarray.DataArray`) – uv distance in wavelength for specific frequency

ragavi.utils.ctext(text, colour='green')¶: Colour some terminal output

ragavi.utils.get_antennas(ms_name)¶

Function to get antennae names from the ANTENNA subtable.

Parameters:	ms_name (`str`) – Name of MS or table
Returns:	ant_names (`xarray.DataArray`) – A `xarray.DataArray` containing names for all the antennas available.

ragavi.utils.get_cmap(cmap, fall_back='coolwarm', src='bokeh')¶: Get Hex colors that form a certain cmap. This function checks for the requested cmap in bokeh.palettes and colorcet.palettes. List of valid names can be found at: https: // colorcet.holoviz.org / user_guide / index.html https: // docs.bokeh.org / en / latest / docs / reference / palettes.html

ragavi.utils.get_diverging_cmap(n_colors, cmap1=None, cmap2=None)¶

Produce n_colors that diverge given two different colourmaps. This function depends on pl.diverging_palettes whose doc can be found at: https: // docs.bokeh.org / en / latest / docs / reference / palettes.html cmap1: : obj: str

Name of the first colourmap to use

cmap2: : obj: str: Name of the second colourmap to use
n_colors: : obj: int: Number of colours to generate.

Returns:	colors (: obj: list) – A list of size n_colors containing the diverging colours

ragavi.utils.get_fields(ms_name)¶

Get field names from the FIELD subtable.

Parameters:	ms_name (`str`) – Name of MS or table
Returns:	field_names (`xarray.DataArray`) – String names for the available fields

ragavi.utils.get_flags(xds_table_obj, corr=None, chan=slice(0, None, None))¶

Get Flag values from the FLAG column. Allow for selections in the channel dimension or the correlation dimension

Parameters:	corr (`int`) – Correlation number to select. xds_table_obj (`xarray.Dataset`) – MS as xarray dataset from xarrayms
Returns:	flags (`xarray.DataArray`) – Data array containing values from FLAG column selected by correlation if index is available.

ragavi.utils.get_frequencies(ms_name, spwid=None, chan=None, cbin=None)¶

Function to get channel frequencies from the SPECTRAL_WINDOW subtable

Parameters:

chan (slice or numpy.ndarray) – A slice object or numpy array to select some or all of the channels. Default is all the channels
cbin (int) – Number of channels to be binned together. If a value is provided, averaging is assumed to be turned on
ms_name (str) – Name of MS or table
spwid (int of slice) – Spectral window id number. Defaults to 0. If slicer is specified, frequencies from a range of spectral windows will be returned.

Returns:

frequencies (xarray.DataArray) – Channel centre frequencies for specified spectral window or all the frequencies for all spectral windows if one is not specified

ragavi.utils.get_linear_cmap(cmap, n, fall_back='coolwarm')¶

Produce n that differ linearly from a given colormap This function depends on pl.linear_palettes whose doc be found at: https: // docs.bokeh.org / en / latest / docs / reference / palettes.html cmap: : obj: str

The colourmap chosen

n: : obj: int: Number of colours to generate

Returns:	colors (: obj: list) – A list of size n containing the linear colours

ragavi.utils.get_polarizations(ms_name)¶

Get the type of polarizations available in the measurement set

Parameters:	ms_name (`str`) – Name of MS / table
Returns:	cor2stokes (`list`) – Returns a list containing the types of correlation

ragavi.utils.name_2id(tab_name, field_name)¶

Translate field name to field id

Parameters:	tab_name (:obj:str`) – MS or Table name field_name (`str`) – Field name to convert to field ID
Returns:	field_id (`int`) – Integer field id

ragavi.utils.resolve_ranges(inp)¶

Create a TAQL string that can be parsed given a range of values

Parameters:

inp (str) –

A range of values to be constructed. Can be in the form of: “5”, “5,6,7”, “5~7” (inclusive range), “5:8” (exclusive range),

”5:” (from 5 to last)

Returns: res (str) – Interval string conforming to TAQL sets and intervals as shown in Casa TAQL Notes

ragavi.utils.slice_data(inp)¶

Creates a slicer for an array. To be used to get a data subset such as correlation or channel subsets.

Parameters:	inp (`str`) – This can be of the form “5”, “10~20” (10 to 20 inclusive), “10:21” (same), “10:” (from 10 to end), “:10:2” (0 to 9 inclusive, stepped by 2), “~9:2” (same)
Returns:	sl (`slice`) – slicer for an iterable object

ragavi.utils.time_convert(xdata)¶

Convert time from MJD to UTC time

Parameters:	xdata (`xarray.DataArray`) – TIME column from the MS or table xarray dataset in MJD format.
Returns:	newtime (`xarray.DataArray`) – TIME column in a more human readable UTC format. Stored as `numpy.datetime` type.

ragavi.utils.time_wrapper(func)¶: A decorator function to compute the execution time of a function

ragavi.utils.update_log_levels(in_logger, level)¶: Change the logging level of the parent plotter

ragavi.utils.update_logfile_name(in_logger, new_name)¶: Change the name of the resulting logfile