qusp.target module

Provides support for working with BOSS targets.

In qusp, a target is identified by a unique plate-mjd-fiber. They are implemented as dictionaries and must have at least ‘plate’, ‘mjd’, and ‘fiber’ keys specified. The Target model is designed to be flexible, in that other attributes can be added to targets as needed.

Examples

Construct a target from a string identifier:

target = qusp.target.Target.from_string('plate-mjd-fiber')

Construct a target from a dictionary:

target = qusp.target.Target({'target':'plate-mjd-fiber'})

Read a target list along with ra, dec, and z columns:

targets = qusp.target.load_target_list(filename,
    fields=[('ra', float, 1), ('dec', float, 2), ('z', float, 3)])

Save a target list along with z and sn fields:

qusp.target.save_target_list(filename, targets, fields=['z', 'sn'])

Iterate over combined spectra for a list targets:

for target, spectrum in qusp.target.get_combined_spectra(targets):
    ...

Iterate over plates for a list of targets:

for target, spplate in qusp.target.get_target_plates(targets):
    spectrum = qusp.read_combined_spectrum(spplate, target)
    ...
class qusp.target.Target(*args, **kwargs)

Bases: dict

Represents a BOSS target.

Parameters:
  • args – Variable length argument list.
  • kwargs – Arbitrary keyword arguments.
Raises:

AssertionError – if ‘target’ key is not specified
classmethod from_plate_mjd_fiber(plate, mjd, fiber)

Returns a Target object constructed from plate, mjd, fiber.

Parameters:
  • plate (int) – target’s plate id
  • mjd (int) – mjd observation
  • fiber (int) – target’s fiber id
Returns:

Target object
classmethod from_string(target_string)

Returns a Target object constructed from a target string identifier.

Parameters:target_string (str) – a target string identifier.
Returns:Target object
to_string()

Returns the standard plate-mjd-fiber string represntation of the target.

Returns:plate-mjd-fiber string represntation of target
qusp.target.add_args(parser)

Adds arguments to the provided command-line parser.

Parameters:parser (argparse.ArgumentParser) – an argument parser
qusp.target.get_combined_spectra(targets, paths=None, sort=True, verbose=False, tpcorr=None)

A generator that yields (target, spectrum) tuples for the provided list of targets. With sort=True, the targets will be sorted by plate-mjd-fiber to reduce the number of io operations.

Parameters:
  • targets (Target) – list of Target objects to iterate through.
  • boss_path (str, optional) – path to boss data directory. Default is to look this up using env var.
  • sort (bool, optional) – Whether or not to sort the provided targets by plate-mjd-fiber. Defaults to True.
  • verbose (bool, optional) – Whether or not to print verbose output. Defaults to False.
Yields:

The next tuple (target, spectrum), where target is a Target and spectrum is a qusp.spectrum.Spectrum that corresponds to the target’s coadded spectrum.
qusp.target.get_combined_spectrum(target, paths=None)

Returns the coadded spectrum of the specified target.

Parameters:
  • target (Target) – a target
  • paths (qusp.paths.Paths, optional) – paths object that knows where the location of the boss data dir.
Returns:

Coadded spectrum of the specified target.
qusp.target.get_corrected_spectrum(target, tpcorr, paths=None)

Returns the coadded spectrum of the specified target.

Parameters:
  • target (Target) – a target
  • tpcorr (hdf5 File object) – hdf5 file with throughput corrections
  • paths (qusp.paths.Paths, optional) – paths object that knows where the location of the boss data dir.
Returns:

Coadded spectrum of the specified target.
qusp.target.get_lite_spectra(targets)
qusp.target.get_lite_spectrum(target, paths=None)
qusp.target.get_target_plates(targets, boss_path=None, sort=True, verbose=False)

A generator that yields (target,spplate) tuples for the provided list of targets. With sort=True, the targets will be sorted by plate-mjd-fiber to reduce the number of io operations.

Parameters:
  • targets (Target) – list of Target objects to iterate through.
  • boss_path (str, optional) – path to boss data directory. Default is to look this up using env var.
  • sort (bool, optional) – Whether or not to sort the provided targets by plate-mjd-fiber. Defaults to True.
  • verbose (bool, optional) – Whether or not to print verbose output. Defaults to False.
Yields:

The next tuple (target, spplate), where target is a Target and spplate is the corresponding FITS file containing its coadded spectrum from the list of targets.
qusp.target.load_target_list(filename, fields=None, verbose=False)

Loads a target data from a text file.

The first column must be plate-mjd-fiber target identifier. Use the fields argument to specify additional columns to read. Must specify a (name, type, column index) tuple for each field.

Parameters:
  • filename (str) – The filename to load.
  • fields (list, optional) – A list of columns to read, see example. Defaults to None.
  • verbose (bool, optional) – Whether or not to print verbose output. Defaults to False.
Returns:

list of Target objects.
qusp.target.load_target_list_from_args(args, fields=None)

Loads a target list from a text file specified using the default target arguments.

Parameters:
  • args (argparse.Namespace) – argparse argument namespace
  • fields (list, optional) – A list of columns to read, see example. Defaults to None.
Returns:

list of Target objects.
qusp.target.save_target_list(filename, targets, fields=None, verbose=False)

Writes a list of targets to the provided file.

By default, only the target plate-mjd-fiber is written to file. Use the fields argument to specify additional target fields to save.

Parameters:
  • filename (str) – The filename of the output text file to create.
  • targets (Target) – A list of Target objects to save.
  • fields (list, optional) – A list of Target keys to annotate output list. Defaults to None.
  • verbose (bool, optional) – Whether or not to print verbose output. Defaults to False.