MetadataTranslator

class astro_metadata_translator.MetadataTranslator(header, filename=None)

Bases: object

Per-instrument metadata translation support

Parameters:
header : dict-like

Representation of an instrument header that can be manipulated as if it was a dict.

filename : str, optional

Name of the file whose header is being translated. For some datasets with missing header information this can sometimes allow for some fixups in translations.

Attributes Summary

default_resource_package Module name to use to locate the correction resources.
default_resource_root Default package resource path root to use to locate header correction files within the default_resource_package package.
default_search_path Default search path to use to locate header correction files.
supported_instrument Name of instrument understood by this translation class.
translators All registered metadata translation classes.

Methods Summary

are_keys_ok(keywords) Are the supplied keys all present and defined?
can_translate(header[, filename]) Indicate whether this translation class can translate the supplied header.
can_translate_with_options(header, options) Helper method for can_translate allowing options.
cards_used() Cards used during metadata extraction.
defined_in_this_class(name) Report if the specified class attribute is defined specifically in this class.
determine_translator(header[, filename]) Determine a translation class by examining the header
is_key_ok(keyword) Return True if the value associated with the named keyword is present in this header and defined.
is_keyword_defined(header, keyword) Return True if the value associated with the named keyword is present in the supplied header and defined.
quantity_from_card(keywords, unit[, …]) Calculate a Astropy Quantity from a header card and a unit.
resource_root() Package resource to use to locate correction resources within an installed package.
search_paths() Search paths to use when searching for header fix up correction files.
to_altaz_begin() Return value of altaz_begin from headers.
to_boresight_airmass() Return value of boresight_airmass from headers.
to_boresight_rotation_angle() Return value of boresight_rotation_angle from headers.
to_boresight_rotation_coord() Return value of boresight_rotation_coord from headers.
to_dark_time() Return value of dark_time from headers.
to_datetime_begin() Return value of datetime_begin from headers.
to_datetime_end() Return value of datetime_end from headers.
to_detector_exposure_id() Return value of detector_exposure_id from headers.
to_detector_group() Return value of detector_group from headers.
to_detector_name() Return value of detector_name from headers.
to_detector_num() Return value of detector_num from headers.
to_detector_serial() Return value of detector_serial from headers.
to_detector_unique_name() Return a unique name for the detector.
to_exposure_id() Return value of exposure_id from headers.
to_exposure_time() Return value of exposure_time from headers.
to_instrument() Return value of instrument from headers.
to_location() Return value of location from headers.
to_object() Return value of object from headers.
to_observation_id() Return value of observation_id from headers.
to_observation_type() Return value of observation_type from headers.
to_physical_filter() Return value of physical_filter from headers.
to_pressure() Return value of pressure from headers.
to_relative_humidity() Return value of relative_humidity from headers.
to_science_program() Return value of science_program from headers.
to_telescope() Return value of telescope from headers.
to_temperature() Return value of temperature from headers.
to_tracking_radec() Return value of tracking_radec from headers.
to_visit_id() Return value of visit_id from headers.
validate_value(value, default[, minimum, …]) Validate the supplied value, returning a new value if out of range

Attributes Documentation

default_resource_package = 'astro_metadata_translator'

Module name to use to locate the correction resources.

default_resource_root = None

Default package resource path root to use to locate header correction files within the default_resource_package package.

default_search_path = None

Default search path to use to locate header correction files.

supported_instrument = None

Name of instrument understood by this translation class.

translators = {'DECam': <class 'astro_metadata_translator.translators.decam.DecamTranslator'>, 'HSC': <class 'astro_metadata_translator.translators.hsc.HscTranslator'>, 'MegaPrime': <class 'astro_metadata_translator.translators.megaprime.MegaPrimeTranslator'>, 'SDSS': <class 'astro_metadata_translator.translators.sdss.SdssTranslator'>, 'SuprimeCam': <class 'astro_metadata_translator.translators.suprimecam.SuprimeCamTranslator'>}

All registered metadata translation classes.

Methods Documentation

are_keys_ok(keywords)

Are the supplied keys all present and defined?

Parameters:
keywords : iterable of str

Keywords to test.

Returns:
all_ok : bool

True if all supplied keys are present and defined.

classmethod can_translate(header, filename=None)

Indicate whether this translation class can translate the supplied header.

Parameters:
header : dict-like

Header to convert to standardized form.

filename : str, optional

Name of file being translated.

Returns:
can : bool

True if the header is recognized by this class. False otherwise.

classmethod can_translate_with_options(header, options, filename=None)

Helper method for can_translate allowing options.

Parameters:
header : dict-like

Header to convert to standardized form.

options : dict

Headers to try to determine whether this header can be translated by this class. If a card is found it will be compared with the expected value and will return that comparison. Each card will be tried in turn until one is found.

filename : str, optional

Name of file being translated.

Returns:
can : bool

True if the header is recognized by this class. False otherwise.

Notes

Intended to be used from within can_translate implementations for specific translators. Is not intended to be called directly from determine_translator.

cards_used()

Cards used during metadata extraction.

Returns:
used : frozenset of str

Cards used when extracting metadata.

classmethod defined_in_this_class(name)

Report if the specified class attribute is defined specifically in this class.

Parameters:
name : str

Name of the attribute to test.

Returns:
in_class : bool

True if there is a attribute of that name defined in this specific subclass. False if the method is not defined in this specific subclass but is defined in a parent class. Returns None if the attribute is not defined anywhere in the class hierarchy (which can happen if translators have typos in their mapping tables).

Notes

Retrieves the attribute associated with the given name. Then looks in all the parent classes to determine whether that attribute comes from a parent class or from the current class. Attributes are compared using id().

classmethod determine_translator(header, filename=None)

Determine a translation class by examining the header

Parameters:
header : dict-like

Representation of a header.

filename : str, optional

Name of file being translated.

Returns:
translator : MetadataTranslator

Translation class that knows how to extract metadata from the supplied header.

Raises:
ValueError

None of the registered translation classes understood the supplied header.

is_key_ok(keyword)

Return True if the value associated with the named keyword is present in this header and defined.

Parameters:
keyword : str

Keyword to check against header.

Returns:
is_ok : bool

True if the header is present and not-None. False otherwise.

static is_keyword_defined(header, keyword)

Return True if the value associated with the named keyword is present in the supplied header and defined.

Parameters:
header : dict-lik

Header to use as reference.

keyword : str

Keyword to check against header.

Returns:
is_defined : bool

True if the header is present and not-None. False otherwise.

quantity_from_card(keywords, unit, default=None, minimum=None, maximum=None, checker=None)

Calculate a Astropy Quantity from a header card and a unit.

Parameters:
keywords : str or list of str

Keyword to use from header. If a list each keyword will be tried in turn until one matches.

unit : astropy.units.UnitBase

Unit of the item in the header.

default : float, optional

Default value to use if the header value is invalid. Assumed to be in the same units as the value expected in the header. If None, no default value is used.

minimum : float, optional

Minimum possible valid value, optional. If the calculated value is below this value, the default value will be used.

maximum : float, optional

Maximum possible valid value, optional. If the calculated value is above this value, the default value will be used.

checker : function, optional

Callback function to be used by the translator method in case the keyword is not present. Function will be executed as if it is a method of the translator class. Running without raising an exception will allow the default to be used. Should usually raise KeyError.

Returns:
q : astropy.units.Quantity

Quantity representing the header value.

Raises:
KeyError

The supplied header key is not present.

resource_root()

Package resource to use to locate correction resources within an installed package.

Returns:
resource_package : str

Package resource name. None if no package resource are to be used.

resource_root : str

The name of the resource root. None if no package resources are to be used.

search_paths()

Search paths to use when searching for header fix up correction files.

Returns:
paths : list

Directory paths to search. Can be an empty list if no special directories are defined.

Notes

Uses the classes default_search_path property if defined.

to_altaz_begin()

Return value of altaz_begin from headers.

Telescope boresight azimuth and elevation at start of observation.

Returns:
altaz_begin : astropy.coordinates.AltAz

The translated property.

to_boresight_airmass()

Return value of boresight_airmass from headers.

Airmass of the boresight of the telescope.

Returns:
boresight_airmass : float

The translated property.

to_boresight_rotation_angle()

Return value of boresight_rotation_angle from headers.

Angle of the instrument in boresight_rotation_coord frame.

Returns:
boresight_rotation_angle : astropy.coordinates.Angle

The translated property.

to_boresight_rotation_coord()

Return value of boresight_rotation_coord from headers.

Coordinate frame of the instrument rotation angle (options: sky, unknown).

Returns:
boresight_rotation_coord : str

The translated property.

to_dark_time()

Return value of dark_time from headers.

Duration of the exposure with shutter closed (seconds).

Returns:
dark_time : astropy.units.Quantity

The translated property.

to_datetime_begin()

Return value of datetime_begin from headers.

Time of the start of the observation.

Returns:
datetime_begin : astropy.time.Time

The translated property.

to_datetime_end()

Return value of datetime_end from headers.

Time of the end of the observation.

Returns:
datetime_end : astropy.time.Time

The translated property.

to_detector_exposure_id()

Return value of detector_exposure_id from headers.

Unique integer identifier for this detector in this exposure.

Returns:
detector_exposure_id : int

The translated property.

to_detector_group()

Return value of detector_group from headers.

Collection name of which this detector is a part. Can be None if there are no detector groupings.

Returns:
detector_group : str

The translated property.

to_detector_name()

Return value of detector_name from headers.

Name of the detector within the instrument (might not be unique if there are detector groups).

Returns:
detector_name : str

The translated property.

to_detector_num()

Return value of detector_num from headers.

Unique (for instrument) integer identifier for the sensor.

Returns:
detector_num : int

The translated property.

to_detector_serial()

Return value of detector_serial from headers.

Serial number/string associated with this detector.

Returns:
detector_serial : str

The translated property.

to_detector_unique_name()

Return a unique name for the detector.

Base class implementation attempts to combine detector_name with detector_group. Group is only used if not None.

Can be over-ridden by specialist translator class.

Returns:
name : str

detector_group``_``detector_name if detector_group is defined, else the detector_name is assumed to be unique. If neither return a valid value an exception is raised.

Raises:
NotImplementedError

Raised if neither detector_name nor detector_group is defined.

to_exposure_id()

Return value of exposure_id from headers.

Unique (with instrument) integer identifier for this observation.

Returns:
exposure_id : int

The translated property.

to_exposure_time()

Return value of exposure_time from headers.

Duration of the exposure with shutter open (seconds).

Returns:
exposure_time : astropy.units.Quantity

The translated property.

to_instrument()

Return value of instrument from headers.

The instrument used to observe the exposure.

Returns:
instrument : str

The translated property.

to_location()

Return value of location from headers.

Location of the observatory.

Returns:
location : astropy.coordinates.EarthLocation

The translated property.

to_object()

Return value of object from headers.

Object of interest or field name.

Returns:
object : str

The translated property.

to_observation_id()

Return value of observation_id from headers.

Label uniquely identifying this observation (can be related to ‘exposure_id’).

Returns:
observation_id : str

The translated property.

to_observation_type()

Return value of observation_type from headers.

Type of observation (currently: science, dark, flat, bias, focus).

Returns:
observation_type : str

The translated property.

to_physical_filter()

Return value of physical_filter from headers.

The bandpass filter used for this observation.

Returns:
physical_filter : str

The translated property.

to_pressure()

Return value of pressure from headers.

Atmospheric pressure outside the dome.

Returns:
pressure : astropy.units.Quantity

The translated property.

to_relative_humidity()

Return value of relative_humidity from headers.

Relative humidity outside the dome.

Returns:
relative_humidity : float

The translated property.

to_science_program()

Return value of science_program from headers.

Observing program (survey or proposal) identifier.

Returns:
science_program : str

The translated property.

to_telescope()

Return value of telescope from headers.

Full name of the telescope.

Returns:
telescope : str

The translated property.

to_temperature()

Return value of temperature from headers.

Temperature outside the dome.

Returns:
temperature : astropy.units.Quantity

The translated property.

to_tracking_radec()

Return value of tracking_radec from headers.

Requested RA/Dec to track.

Returns:
tracking_radec : astropy.coordinates.SkyCoord

The translated property.

to_visit_id()

Return value of visit_id from headers.

ID of the Visit this Exposure is associated with.

Science observations should essentially always be associated with a visit, but calibration observations may not be.

Returns:
visit_id : int

The translated property.

static validate_value(value, default, minimum=None, maximum=None)

Validate the supplied value, returning a new value if out of range

Parameters:
value : float

Value to be validated.

default : float

Default value to use if supplied value is invalid or out of range. Assumed to be in the same units as the value expected in the header.

minimum : float

Minimum possible valid value, optional. If the calculated value is below this value, the default value will be used.

maximum : float

Maximum possible valid value, optional. If the calculated value is above this value, the default value will be used.

Returns:
value : float

Either the supplied value, or a default value.