Coverage for python/astro_metadata_translator/translator.py: 46%
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1# This file is part of astro_metadata_translator.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the LICENSE file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# Use of this source code is governed by a 3-clause BSD-style
10# license that can be found in the LICENSE file.
12"""Classes and support code for metadata translation."""
14from __future__ import annotations
16__all__ = ("MetadataTranslator", "StubTranslator", "cache_translation")
18import importlib
19import inspect
20import logging
21import math
22import warnings
23from abc import abstractmethod
24from collections.abc import Callable, Iterable, Iterator, Mapping, MutableMapping, Sequence
25from typing import TYPE_CHECKING, Any, ClassVar
27import astropy.io.fits.card
28import astropy.units as u
29from astropy.coordinates import Angle
31from .properties import PROPERTIES, PropertyDefinition
33if TYPE_CHECKING: 33 ↛ 34line 33 didn't jump to line 34, because the condition on line 33 was never true
34 import astropy.coordinates
35 import astropy.time
37log = logging.getLogger(__name__)
39# Location of the root of the corrections resource files
40CORRECTIONS_RESOURCE_ROOT = "corrections"
42"""Cache of version strings indexed by class."""
43_VERSION_CACHE: dict[type, str] = dict()
46def cache_translation(func: Callable, method: str | None = None) -> Callable:
47 """Cache the result of a translation method.
49 Parameters
50 ----------
51 func : `~collections.abc.Callable`
52 Translation method to cache.
53 method : `str`, optional
54 Name of the translation method to cache. Not needed if the decorator
55 is used around a normal method, but necessary when the decorator is
56 being used in a metaclass.
58 Returns
59 -------
60 wrapped : `~collections.abc.Callable`
61 Method wrapped by the caching function.
63 Notes
64 -----
65 Especially useful when a translation uses many other translation
66 methods or involves significant computation.
67 Should be used only on ``to_x()`` methods.
69 .. code-block:: python
71 @cache_translation
72 def to_detector_num(self):
73 ....
74 """
75 name = func.__name__ if method is None else method
77 def func_wrapper(self: MetadataTranslator) -> Any:
78 if name not in self._translation_cache:
79 self._translation_cache[name] = func(self)
80 return self._translation_cache[name]
82 func_wrapper.__doc__ = func.__doc__
83 func_wrapper.__name__ = f"{name}_cached"
84 return func_wrapper
87class MetadataTranslator:
88 """Per-instrument metadata translation support.
90 Parameters
91 ----------
92 header : `dict`-like
93 Representation of an instrument header that can be manipulated
94 as if it was a `dict`.
95 filename : `str`, optional
96 Name of the file whose header is being translated. For some
97 datasets with missing header information this can sometimes
98 allow for some fixups in translations.
99 """
101 # These are all deliberately empty in the base class.
102 name: str | None = None
103 """The declared name of the translator."""
105 default_search_path: Sequence[str] | None = None
106 """Default search path to use to locate header correction files."""
108 default_resource_package = __name__.split(".")[0]
109 """Module name to use to locate the correction resources."""
111 default_resource_root: str | None = None
112 """Default package resource path root to use to locate header correction
113 files within the ``default_resource_package`` package."""
115 _trivial_map: dict[str, str | list[str] | tuple[Any, ...]] = {}
116 """Dict of one-to-one mappings for header translation from standard
117 property to corresponding keyword."""
119 _const_map: dict[str, Any] = {}
120 """Dict defining a constant for specified standard properties."""
122 translators: dict[str, type[MetadataTranslator]] = dict()
123 """All registered metadata translation classes."""
125 supported_instrument: str | None = None
126 """Name of instrument understood by this translation class."""
128 all_properties: dict[str, PropertyDefinition] = {}
129 """All the valid properties for this translator including extensions."""
131 extensions: dict[str, PropertyDefinition] = {}
132 """Extension properties (`str`: `PropertyDefinition`)
134 Some instruments have important properties beyond the standard set; this is
135 the place to declare that they exist, and they will be treated in the same
136 way as the standard set, except that their names will everywhere be
137 prefixed with ``ext_``.
139 Each property is indexed by name (`str`), with a corresponding
140 `PropertyDefinition`.
141 """
143 # Static typing requires that we define the standard dynamic properties
144 # statically.
145 if TYPE_CHECKING: 145 ↛ 146line 145 didn't jump to line 146, because the condition on line 145 was never true
146 to_telescope: ClassVar[Callable[[MetadataTranslator], str]]
147 to_instrument: ClassVar[Callable[[MetadataTranslator], str]]
148 to_location: ClassVar[Callable[[MetadataTranslator], astropy.coordinates.EarthLocation]]
149 to_exposure_id: ClassVar[Callable[[MetadataTranslator], int]]
150 to_visit_id: ClassVar[Callable[[MetadataTranslator], int]]
151 to_physical_filter: ClassVar[Callable[[MetadataTranslator], str]]
152 to_datetime_begin: ClassVar[Callable[[MetadataTranslator], astropy.time.Time]]
153 to_datetime_end: ClassVar[Callable[[MetadataTranslator], astropy.time.Time]]
154 to_exposure_time: ClassVar[Callable[[MetadataTranslator], u.Quantity]]
155 to_dark_time: ClassVar[Callable[[MetadataTranslator], u.Quantity]]
156 to_boresight_airmass: ClassVar[Callable[[MetadataTranslator], float]]
157 to_boresight_rotation_angle: ClassVar[Callable[[MetadataTranslator], u.Quantity]]
158 to_boresight_rotation_coord: ClassVar[Callable[[MetadataTranslator], str]]
159 to_detector_num: ClassVar[Callable[[MetadataTranslator], int]]
160 to_detector_name: ClassVar[Callable[[MetadataTranslator], str]]
161 to_detector_serial: ClassVar[Callable[[MetadataTranslator], str]]
162 to_detector_group: ClassVar[Callable[[MetadataTranslator], str | None]]
163 to_detector_exposure_id: ClassVar[Callable[[MetadataTranslator], int]]
164 to_object: ClassVar[Callable[[MetadataTranslator], str]]
165 to_temperature: ClassVar[Callable[[MetadataTranslator], u.Quantity]]
166 to_pressure: ClassVar[Callable[[MetadataTranslator], u.Quantity]]
167 to_relative_humidity: ClassVar[Callable[[MetadataTranslator], float]]
168 to_tracking_radec: ClassVar[Callable[[MetadataTranslator], astropy.coordinates.SkyCoord]]
169 to_altaz_begin: ClassVar[Callable[[MetadataTranslator], astropy.coordinates.AltAz]]
170 to_science_program: ClassVar[Callable[[MetadataTranslator], str]]
171 to_observation_type: ClassVar[Callable[[MetadataTranslator], str]]
172 to_observation_id: ClassVar[Callable[[MetadataTranslator], str]]
174 @classmethod
175 def defined_in_this_class(cls, name: str) -> bool | None:
176 """Report if the specified class attribute is defined specifically in
177 this class.
179 Parameters
180 ----------
181 name : `str`
182 Name of the attribute to test.
184 Returns
185 -------
186 in_class : `bool`
187 `True` if there is a attribute of that name defined in this
188 specific subclass.
189 `False` if the method is not defined in this specific subclass
190 but is defined in a parent class.
191 Returns `None` if the attribute is not defined anywhere
192 in the class hierarchy (which can happen if translators have
193 typos in their mapping tables).
195 Notes
196 -----
197 Retrieves the attribute associated with the given name.
198 Then looks in all the parent classes to determine whether that
199 attribute comes from a parent class or from the current class.
200 Attributes are compared using :py:func:`id`.
201 """
202 # The attribute to compare.
203 if not hasattr(cls, name):
204 return None
205 attr_id = id(getattr(cls, name))
207 # Get all the classes in the hierarchy
208 mro = list(inspect.getmro(cls))
210 # Remove the first entry from the list since that will be the
211 # current class
212 mro.pop(0)
214 for parent in mro:
215 # Some attributes may only exist in subclasses. Skip base classes
216 # that are missing the attribute (such as object).
217 if hasattr(parent, name):
218 if id(getattr(parent, name)) == attr_id:
219 return False
220 return True
222 @classmethod
223 def _make_const_mapping(cls, property_key: str, constant: Any) -> Callable:
224 """Make a translator method that returns a constant value.
226 Parameters
227 ----------
228 property_key : `str`
229 Name of the property to be calculated (for the docstring).
230 constant : `str` or `numbers.Number`
231 Value to return for this translator.
233 Returns
234 -------
235 f : `~collections.abc.Callable`
236 Function returning the constant.
237 """
239 def constant_translator(self: MetadataTranslator) -> Any:
240 return constant
242 if property_key in cls.all_properties:
243 property_doc = cls.all_properties[property_key].doc
244 return_type = cls.all_properties[property_key].py_type
245 else:
246 return_type = type(constant)
247 property_doc = f"Returns constant value for '{property_key}' property"
249 if return_type.__module__ == "builtins":
250 full_name = return_type.__name__
251 else:
252 full_name = f"{return_type.__module__}.{return_type.__qualname__}"
254 constant_translator.__doc__ = f"""{property_doc}
256 Returns
257 -------
258 translation : `{full_name}`
259 Translated property.
260 """
261 return constant_translator
263 @classmethod
264 def _make_trivial_mapping(
265 cls,
266 property_key: str,
267 header_key: str | Sequence[str],
268 default: Any | None = None,
269 minimum: Any | None = None,
270 maximum: Any | None = None,
271 unit: astropy.unit.Unit | None = None,
272 checker: Callable | None = None,
273 ) -> Callable:
274 """Make a translator method returning a header value.
276 The header value can be converted to a `~astropy.units.Quantity`
277 if desired, and can also have its value validated.
279 See `MetadataTranslator.validate_value()` for details on the use
280 of default parameters.
282 Parameters
283 ----------
284 property_key : `str`
285 Name of the translator to be constructed (for the docstring).
286 header_key : `str` or `list` of `str`
287 Name of the key to look up in the header. If a `list` each
288 key will be tested in turn until one matches. This can deal with
289 header styles that evolve over time.
290 default : `numbers.Number` or `astropy.units.Quantity`, `str`, optional
291 If not `None`, default value to be used if the parameter read from
292 the header is not defined or if the header is missing.
293 minimum : `numbers.Number` or `astropy.units.Quantity`, optional
294 If not `None`, and if ``default`` is not `None`, minimum value
295 acceptable for this parameter.
296 maximum : `numbers.Number` or `astropy.units.Quantity`, optional
297 If not `None`, and if ``default`` is not `None`, maximum value
298 acceptable for this parameter.
299 unit : `astropy.units.Unit`, optional
300 If not `None`, the value read from the header will be converted
301 to a `~astropy.units.Quantity`. Only supported for numeric values.
302 checker : `~collections.abc.Callable`, optional
303 Callback function to be used by the translator method in case the
304 keyword is not present. Function will be executed as if it is
305 a method of the translator class. Running without raising an
306 exception will allow the default to be used. Should usually raise
307 `KeyError`.
309 Returns
310 -------
311 t : `~collections.abc.Callable`
312 Function implementing a translator with the specified
313 parameters.
314 """
315 if property_key in cls.all_properties: 315 ↛ 319line 315 didn't jump to line 319, because the condition on line 315 was never false
316 property_doc = cls.all_properties[property_key].doc
317 return_type = cls.all_properties[property_key].str_type
318 else:
319 return_type = "str` or `numbers.Number"
320 property_doc = f"Map '{header_key}' header keyword to '{property_key}' property"
322 def trivial_translator(self: MetadataTranslator) -> Any:
323 if unit is not None:
324 q = self.quantity_from_card(
325 header_key, unit, default=default, minimum=minimum, maximum=maximum, checker=checker
326 )
327 # Convert to Angle if this quantity is an angle
328 if return_type == "astropy.coordinates.Angle":
329 q = Angle(q)
330 return q
332 keywords = header_key if isinstance(header_key, list) else [header_key]
333 for key in keywords:
334 if self.is_key_ok(key):
335 value = self._header[key]
336 if default is not None and not isinstance(value, str):
337 value = self.validate_value(value, default, minimum=minimum, maximum=maximum)
338 self._used_these_cards(key)
339 break
340 else:
341 # No keywords found, use default, checking first, or raise
342 # A None default is only allowed if a checker is provided.
343 if checker is not None:
344 try:
345 checker(self)
346 except Exception:
347 raise KeyError(f"Could not find {keywords} in header")
348 return default
349 elif default is not None:
350 value = default
351 else:
352 raise KeyError(f"Could not find {keywords} in header")
354 # If we know this is meant to be a string, force to a string.
355 # Sometimes headers represent items as integers which generically
356 # we want as strings (eg OBSID). Sometimes also floats are
357 # written as "NaN" strings.
358 casts = {"str": str, "float": float, "int": int}
359 if return_type in casts and not isinstance(value, casts[return_type]) and value is not None:
360 value = casts[return_type](value)
362 return value
364 # Docstring inheritance means it is confusing to specify here
365 # exactly which header value is being used.
366 trivial_translator.__doc__ = f"""{property_doc}
368 Returns
369 -------
370 translation : `{return_type}`
371 Translated value derived from the header.
372 """
373 return trivial_translator
375 @classmethod
376 def __init_subclass__(cls, **kwargs: Any) -> None:
377 """Register all subclasses with the base class and create dynamic
378 translator methods.
380 The method provides two facilities. Firstly, every subclass
381 of `MetadataTranslator` that includes a ``name`` class property is
382 registered as a translator class that could be selected when automatic
383 header translation is attempted. Only name translator subclasses that
384 correspond to a complete instrument. Translation classes providing
385 generic translation support for multiple instrument translators should
386 not be named.
388 The second feature of this method is to convert simple translations
389 to full translator methods. Sometimes a translation is fixed (for
390 example a specific instrument name should be used) and rather than
391 provide a full ``to_property()`` translation method the mapping can be
392 defined in a class variable named ``_constMap``. Similarly, for
393 one-to-one trivial mappings from a header to a property,
394 ``_trivialMap`` can be defined. Trivial mappings are a dict mapping a
395 generic property to either a header keyword, or a tuple consisting of
396 the header keyword and a dict containing key value pairs suitable for
397 the `MetadataTranslator.quantity_from_card` method.
398 """
399 super().__init_subclass__(**kwargs)
401 # Only register classes with declared names
402 if hasattr(cls, "name") and cls.name is not None:
403 if cls.name in MetadataTranslator.translators: 403 ↛ 404line 403 didn't jump to line 404, because the condition on line 403 was never true
404 log.warning(
405 "%s: Replacing %s translator with %s",
406 cls.name,
407 MetadataTranslator.translators[cls.name],
408 cls,
409 )
410 MetadataTranslator.translators[cls.name] = cls
412 # Check that we have not inherited constant/trivial mappings from
413 # parent class that we have already applied. Empty maps are always
414 # assumed okay
415 const_map = cls._const_map if cls._const_map and cls.defined_in_this_class("_const_map") else {}
416 trivial_map = (
417 cls._trivial_map if cls._trivial_map and cls.defined_in_this_class("_trivial_map") else {}
418 )
420 # Check for shadowing
421 trivials = set(trivial_map.keys())
422 constants = set(const_map.keys())
423 both = trivials & constants
424 if both: 424 ↛ 425line 424 didn't jump to line 425, because the condition on line 424 was never true
425 log.warning("%s: defined in both const_map and trivial_map: %s", cls.__name__, ", ".join(both))
427 all = trivials | constants
428 for name in all:
429 if cls.defined_in_this_class(f"to_{name}"): 429 ↛ 432line 429 didn't jump to line 432, because the condition on line 429 was never true
430 # Must be one of trivial or constant. If in both then constant
431 # overrides trivial.
432 location = "by _trivial_map"
433 if name in constants:
434 location = "by _const_map"
435 log.warning(
436 "%s: %s is defined explicitly but will be replaced %s", cls.__name__, name, location
437 )
439 properties = set(PROPERTIES) | {"ext_" + pp for pp in cls.extensions}
440 cls.all_properties = dict(PROPERTIES)
441 cls.all_properties.update(cls.extensions)
443 # Go through the trival mappings for this class and create
444 # corresponding translator methods
445 for property_key, header_key in trivial_map.items():
446 kwargs = {}
447 if type(header_key) == tuple:
448 kwargs = header_key[1]
449 header_key = header_key[0]
450 translator = cls._make_trivial_mapping(property_key, header_key, **kwargs)
451 method = f"to_{property_key}"
452 translator.__name__ = f"{method}_trivial_in_{cls.__name__}"
453 setattr(cls, method, cache_translation(translator, method=method))
454 if property_key not in properties: 454 ↛ 455line 454 didn't jump to line 455, because the condition on line 454 was never true
455 log.warning(f"Unexpected trivial translator for '{property_key}' defined in {cls}")
457 # Go through the constant mappings for this class and create
458 # corresponding translator methods
459 for property_key, constant in const_map.items():
460 translator = cls._make_const_mapping(property_key, constant)
461 method = f"to_{property_key}"
462 translator.__name__ = f"{method}_constant_in_{cls.__name__}"
463 setattr(cls, method, translator)
464 if property_key not in properties: 464 ↛ 465line 464 didn't jump to line 465, because the condition on line 464 was never true
465 log.warning(f"Unexpected constant translator for '{property_key}' defined in {cls}")
467 def __init__(self, header: Mapping[str, Any], filename: str | None = None) -> None:
468 self._header = header
469 self.filename = filename
470 self._used_cards: set[str] = set()
472 # Prefix to use for warnings about failed translations
473 self._log_prefix_cache: str | None = None
475 # Cache assumes header is read-only once stored in object
476 self._translation_cache: dict[str, Any] = {}
478 @classmethod
479 @abstractmethod
480 def can_translate(cls, header: Mapping[str, Any], filename: str | None = None) -> bool:
481 """Indicate whether this translation class can translate the
482 supplied header.
484 Parameters
485 ----------
486 header : `dict`-like
487 Header to convert to standardized form.
488 filename : `str`, optional
489 Name of file being translated.
491 Returns
492 -------
493 can : `bool`
494 `True` if the header is recognized by this class. `False`
495 otherwise.
496 """
497 raise NotImplementedError()
499 @classmethod
500 def can_translate_with_options(
501 cls, header: Mapping[str, Any], options: dict[str, Any], filename: str | None = None
502 ) -> bool:
503 """Determine if a header can be translated with different criteria.
505 Parameters
506 ----------
507 header : `dict`-like
508 Header to convert to standardized form.
509 options : `dict`
510 Headers to try to determine whether this header can
511 be translated by this class. If a card is found it will
512 be compared with the expected value and will return that
513 comparison. Each card will be tried in turn until one is
514 found.
515 filename : `str`, optional
516 Name of file being translated.
518 Returns
519 -------
520 can : `bool`
521 `True` if the header is recognized by this class. `False`
522 otherwise.
524 Notes
525 -----
526 Intended to be used from within `can_translate` implementations
527 for specific translators. Is not intended to be called directly
528 from `determine_translator`.
529 """
530 for card, value in options.items():
531 if card in header:
532 return header[card] == value
533 return False
535 @classmethod
536 def determine_translator(
537 cls, header: Mapping[str, Any], filename: str | None = None
538 ) -> type[MetadataTranslator]:
539 """Determine a translation class by examining the header.
541 Parameters
542 ----------
543 header : `dict`-like
544 Representation of a header.
545 filename : `str`, optional
546 Name of file being translated.
548 Returns
549 -------
550 translator : `MetadataTranslator`
551 Translation class that knows how to extract metadata from
552 the supplied header.
554 Raises
555 ------
556 ValueError
557 None of the registered translation classes understood the supplied
558 header.
559 """
560 file_msg = ""
561 if filename is not None:
562 file_msg = f" from {filename}"
563 for name, trans in cls.translators.items():
564 if trans.can_translate(header, filename=filename):
565 log.debug("Using translation class %s%s", name, file_msg)
566 return trans
567 else:
568 raise ValueError(
569 f"None of the registered translation classes {list(cls.translators.keys())}"
570 f" understood this header{file_msg}"
571 )
573 @classmethod
574 def translator_version(cls) -> str:
575 """Return the version string for this translator class.
577 Returns
578 -------
579 version : `str`
580 String identifying the version of this translator.
582 Notes
583 -----
584 Assumes that the version is available from the ``__version__``
585 variable in the parent module. If this is not the case a translator
586 should subclass this method.
587 """
588 if cls in _VERSION_CACHE:
589 return _VERSION_CACHE[cls]
591 version = "unknown"
592 module_name = cls.__module__
593 components = module_name.split(".")
594 while components:
595 # This class has already been imported so importing it
596 # should work.
597 module = importlib.import_module(".".join(components))
598 if hasattr(module, v := "__version__"):
599 version = getattr(module, v)
600 if version == "unknown":
601 # LSST software will have a fingerprint
602 if hasattr(module, v := "__fingerprint__"):
603 version = getattr(module, v)
604 break
605 else:
606 # Remove last component from module name and try again
607 components.pop()
609 _VERSION_CACHE[cls] = version
610 return version
612 @classmethod
613 def fix_header(
614 cls, header: MutableMapping[str, Any], instrument: str, obsid: str, filename: str | None = None
615 ) -> bool:
616 """Apply global fixes to a supplied header.
618 Parameters
619 ----------
620 header : `dict`
621 The header to correct. Correction is in place.
622 instrument : `str`
623 The name of the instrument.
624 obsid : `str`
625 Unique observation identifier associated with this header.
626 Will always be provided.
627 filename : `str`, optional
628 Filename associated with this header. May not be set since headers
629 can be fixed independently of any filename being known.
631 Returns
632 -------
633 modified : `bool`
634 `True` if a correction was applied.
636 Notes
637 -----
638 This method is intended to support major discrepancies in headers
639 such as:
641 * Periods of time where headers are known to be incorrect in some
642 way that can be fixed either by deriving the correct value from
643 the existing value or understanding the that correction is static
644 for the given time. This requires that the date header is
645 known.
646 * The presence of a certain value is always wrong and should be
647 corrected with a new static value regardless of date.
649 It is assumed that one off problems with headers have been applied
650 before this method is called using the per-obsid correction system.
652 Usually called from `astro_metadata_translator.fix_header`.
654 For log messages, do not assume that the filename will be present.
655 Always write log messages to fall back on using the ``obsid`` if
656 ``filename`` is `None`.
657 """
658 return False
660 @staticmethod
661 def _construct_log_prefix(obsid: str, filename: str | None = None) -> str:
662 """Construct a log prefix string from the obsid and filename.
664 Parameters
665 ----------
666 obsid : `str`
667 The observation identifier.
668 filename : `str`, optional
669 The filename associated with the header being translated.
670 Can be `None`.
671 """
672 if filename:
673 return f"{filename}({obsid})"
674 return obsid
676 @property
677 def _log_prefix(self) -> str:
678 """Return standard prefix that can be used for log messages to report
679 useful context.
681 Will be either the filename and obsid, or just the obsid depending
682 on whether a filename is known.
684 Returns
685 -------
686 prefix : `str`
687 The prefix to use.
688 """
689 if self._log_prefix_cache is None:
690 # Protect against the unfortunate event of the obsid failing to
691 # be calculated. This should be rare but should not prevent a log
692 # message from appearing.
693 try:
694 obsid = self.to_observation_id()
695 except Exception:
696 obsid = "unknown_obsid"
697 self._log_prefix_cache = self._construct_log_prefix(obsid, self.filename)
698 return self._log_prefix_cache
700 def _used_these_cards(self, *args: str) -> None:
701 """Indicate that the supplied cards have been used for translation.
703 Parameters
704 ----------
705 args : sequence of `str`
706 Keywords used to process a translation.
707 """
708 self._used_cards.update(set(args))
710 def cards_used(self) -> frozenset[str]:
711 """Cards used during metadata extraction.
713 Returns
714 -------
715 used : `frozenset` of `str`
716 Cards used when extracting metadata.
717 """
718 return frozenset(self._used_cards)
720 @staticmethod
721 def validate_value(
722 value: float, default: float, minimum: float | None = None, maximum: float | None = None
723 ) -> float:
724 """Validate the supplied value, returning a new value if out of range.
726 Parameters
727 ----------
728 value : `float`
729 Value to be validated.
730 default : `float`
731 Default value to use if supplied value is invalid or out of range.
732 Assumed to be in the same units as the value expected in the
733 header.
734 minimum : `float`
735 Minimum possible valid value, optional. If the calculated value
736 is below this value, the default value will be used.
737 maximum : `float`
738 Maximum possible valid value, optional. If the calculated value
739 is above this value, the default value will be used.
741 Returns
742 -------
743 value : `float`
744 Either the supplied value, or a default value.
745 """
746 if value is None or math.isnan(value):
747 value = default
748 else:
749 if minimum is not None and value < minimum:
750 value = default
751 elif maximum is not None and value > maximum:
752 value = default
753 return value
755 @staticmethod
756 def is_keyword_defined(header: Mapping[str, Any], keyword: str | None) -> bool:
757 """Return `True` if the value associated with the named keyword is
758 present in the supplied header and defined.
760 Parameters
761 ----------
762 header : `dict`-lik
763 Header to use as reference.
764 keyword : `str`
765 Keyword to check against header.
767 Returns
768 -------
769 is_defined : `bool`
770 `True` if the header is present and not-`None`. `False` otherwise.
771 """
772 if keyword is None or keyword not in header:
773 return False
775 if header[keyword] is None:
776 return False
778 # Special case Astropy undefined value
779 if isinstance(header[keyword], astropy.io.fits.card.Undefined):
780 return False
782 return True
784 def resource_root(self) -> tuple[str | None, str | None]:
785 """Return package resource to use to locate correction resources within
786 an installed package.
788 Returns
789 -------
790 resource_package : `str`
791 Package resource name. `None` if no package resource are to be
792 used.
793 resource_root : `str`
794 The name of the resource root. `None` if no package resources
795 are to be used.
796 """
797 return (self.default_resource_package, self.default_resource_root)
799 def search_paths(self) -> list[str]:
800 """Search paths to use when searching for header fix up correction
801 files.
803 Returns
804 -------
805 paths : `list`
806 Directory paths to search. Can be an empty list if no special
807 directories are defined.
809 Notes
810 -----
811 Uses the classes ``default_search_path`` property if defined.
812 """
813 if self.default_search_path is not None:
814 return [p for p in self.default_search_path]
815 return []
817 def is_key_ok(self, keyword: str | None) -> bool:
818 """Return `True` if the value associated with the named keyword is
819 present in this header and defined.
821 Parameters
822 ----------
823 keyword : `str`
824 Keyword to check against header.
826 Returns
827 -------
828 is_ok : `bool`
829 `True` if the header is present and not-`None`. `False` otherwise.
830 """
831 return self.is_keyword_defined(self._header, keyword)
833 def are_keys_ok(self, keywords: Iterable[str]) -> bool:
834 """Are the supplied keys all present and defined?.
836 Parameters
837 ----------
838 keywords : iterable of `str`
839 Keywords to test.
841 Returns
842 -------
843 all_ok : `bool`
844 `True` if all supplied keys are present and defined.
845 """
846 for k in keywords:
847 if not self.is_key_ok(k):
848 return False
849 return True
851 def quantity_from_card(
852 self,
853 keywords: str | Sequence[str],
854 unit: u.Unit,
855 default: float | None = None,
856 minimum: float | None = None,
857 maximum: float | None = None,
858 checker: Callable | None = None,
859 ) -> u.Quantity:
860 """Calculate a Astropy Quantity from a header card and a unit.
862 Parameters
863 ----------
864 keywords : `str` or `list` of `str`
865 Keyword to use from header. If a list each keyword will be tried
866 in turn until one matches.
867 unit : `astropy.units.UnitBase`
868 Unit of the item in the header.
869 default : `float`, optional
870 Default value to use if the header value is invalid. Assumed
871 to be in the same units as the value expected in the header. If
872 None, no default value is used.
873 minimum : `float`, optional
874 Minimum possible valid value, optional. If the calculated value
875 is below this value, the default value will be used.
876 maximum : `float`, optional
877 Maximum possible valid value, optional. If the calculated value
878 is above this value, the default value will be used.
879 checker : `~collections.abc.Callable`, optional
880 Callback function to be used by the translator method in case the
881 keyword is not present. Function will be executed as if it is
882 a method of the translator class. Running without raising an
883 exception will allow the default to be used. Should usually raise
884 `KeyError`.
886 Returns
887 -------
888 q : `astropy.units.Quantity`
889 Quantity representing the header value.
891 Raises
892 ------
893 KeyError
894 The supplied header key is not present.
895 """
896 keyword_list = [keywords] if isinstance(keywords, str) else list(keywords)
897 for k in keyword_list:
898 if self.is_key_ok(k):
899 value = self._header[k]
900 keyword = k
901 break
902 else:
903 if checker is not None:
904 try:
905 checker(self)
906 value = default
907 if value is not None:
908 value = u.Quantity(value, unit=unit)
909 return value
910 except Exception:
911 pass
912 raise KeyError(f"Could not find {keywords} in header")
913 if isinstance(value, str):
914 # Sometimes the header has the wrong type in it but this must
915 # be a number if we are creating a quantity.
916 value = float(value)
917 self._used_these_cards(keyword)
918 if default is not None:
919 value = self.validate_value(value, default, maximum=maximum, minimum=minimum)
920 return u.Quantity(value, unit=unit)
922 def _join_keyword_values(self, keywords: Iterable[str], delim: str = "+") -> str:
923 """Join values of all defined keywords with the specified delimiter.
925 Parameters
926 ----------
927 keywords : iterable of `str`
928 Keywords to look for in header.
929 delim : `str`, optional
930 Character to use to join the values together.
932 Returns
933 -------
934 joined : `str`
935 String formed from all the keywords found in the header with
936 defined values joined by the delimiter. Empty string if no
937 defined keywords found.
938 """
939 values = []
940 for k in keywords:
941 if self.is_key_ok(k):
942 values.append(self._header[k])
943 self._used_these_cards(k)
945 if values:
946 joined = delim.join(str(v) for v in values)
947 else:
948 joined = ""
950 return joined
952 @cache_translation
953 def to_detector_unique_name(self) -> str:
954 """Return a unique name for the detector.
956 Base class implementation attempts to combine ``detector_name`` with
957 ``detector_group``. Group is only used if not `None`.
959 Can be over-ridden by specialist translator class.
961 Returns
962 -------
963 name : `str`
964 ``detector_group``_``detector_name`` if ``detector_group`` is
965 defined, else the ``detector_name`` is assumed to be unique.
966 If neither return a valid value an exception is raised.
968 Raises
969 ------
970 NotImplementedError
971 Raised if neither detector_name nor detector_group is defined.
972 """
973 name = self.to_detector_name()
974 group = self.to_detector_group()
976 if group is None and name is None:
977 raise NotImplementedError("Can not determine unique name from detector_group and detector_name")
979 if group is not None:
980 return f"{group}_{name}"
982 return name
984 @cache_translation
985 def to_exposure_group(self) -> str | None:
986 """Return the group label associated with this exposure.
988 Base class implementation returns the ``exposure_id`` in string
989 form. A subclass may do something different.
991 Returns
992 -------
993 name : `str`
994 The ``exposure_id`` converted to a string.
995 """
996 exposure_id = self.to_exposure_id()
997 if exposure_id is None:
998 # mypy does not think this can ever happen but play it safe
999 # with subclasses.
1000 return None # type: ignore
1001 else:
1002 return str(exposure_id)
1004 @cache_translation
1005 def to_observation_reason(self) -> str:
1006 """Return the reason this observation was taken.
1008 Base class implementation returns the ``science`` if the
1009 ``observation_type`` is science, else ``unknown``.
1010 A subclass may do something different.
1012 Returns
1013 -------
1014 name : `str`
1015 The reason for this observation.
1016 """
1017 obstype = self.to_observation_type()
1018 if obstype == "science":
1019 return "science"
1020 return "unknown"
1022 @cache_translation
1023 def to_observing_day(self) -> int:
1024 """Return the YYYYMMDD integer corresponding to the observing day.
1026 Base class implementation uses the TAI date of the start of the
1027 observation.
1029 Returns
1030 -------
1031 day : `int`
1032 The observing day as an integer of form YYYYMMDD. If the header
1033 is broken and is unable to obtain a date of observation, ``0``
1034 is returned and the assumption is made that the problem will
1035 be caught elsewhere.
1036 """
1037 datetime_begin = self.to_datetime_begin()
1038 if datetime_begin is None:
1039 return 0
1040 return int(datetime_begin.tai.strftime("%Y%m%d"))
1042 @cache_translation
1043 def to_observation_counter(self) -> int:
1044 """Return an integer corresponding to how this observation relates
1045 to other observations.
1047 Base class implementation returns ``0`` to indicate that it is not
1048 known how an observatory will define a counter. Some observatories
1049 may not use the concept, others may use a counter that increases
1050 for every observation taken for that instrument, and others may
1051 define it to be a counter within an observing day.
1053 Returns
1054 -------
1055 sequence : `int`
1056 The observation counter. Always ``0`` for this implementation.
1057 """
1058 return 0
1060 @cache_translation
1061 def to_group_counter_start(self) -> int:
1062 """Return the observation counter of the observation that began
1063 this group.
1065 The definition of the relevant group is up to the metadata
1066 translator. It can be the first observation in the exposure_group
1067 or the first observation in the visit, but must be derivable
1068 from the metadata of this observation.
1070 Returns
1071 -------
1072 counter : `int`
1073 The observation counter for the start of the relevant group.
1074 Default implementation always returns the observation counter
1075 of this observation.
1076 """
1077 return self.to_observation_counter()
1079 @cache_translation
1080 def to_group_counter_end(self) -> int:
1081 """Return the observation counter of the observation that ends
1082 this group.
1084 The definition of the relevant group is up to the metadata
1085 translator. It can be the last observation in the exposure_group
1086 or the last observation in the visit, but must be derivable
1087 from the metadata of this observation. It is of course possible
1088 that the last observation in the group does not exist if a sequence
1089 of observations was not completed.
1091 Returns
1092 -------
1093 counter : `int`
1094 The observation counter for the end of the relevant group.
1095 Default implementation always returns the observation counter
1096 of this observation.
1097 """
1098 return self.to_observation_counter()
1100 @cache_translation
1101 def to_has_simulated_content(self) -> bool:
1102 """Return a boolean indicating whether any part of the observation
1103 was simulated.
1105 Returns
1106 -------
1107 is_simulated : `bool`
1108 `True` if this exposure has simulated content. This can be
1109 if some parts of the metadata or data were simulated. Default
1110 implementation always returns `False`.
1111 """
1112 return False
1114 @cache_translation
1115 def to_focus_z(self) -> u.Quantity:
1116 """Return a default defocal distance of 0.0 mm if there is no
1117 keyword for defocal distance in the header. The default
1118 keyword for defocal distance is ``FOCUSZ``.
1120 Returns
1121 -------
1122 focus_z: `astropy.units.Quantity`
1123 The defocal distance from header or the 0.0mm default
1124 """
1125 return 0.0 * u.mm
1127 @classmethod
1128 def determine_translatable_headers(
1129 cls, filename: str, primary: MutableMapping[str, Any] | None = None
1130 ) -> Iterator[MutableMapping[str, Any]]:
1131 """Given a file return all the headers usable for metadata translation.
1133 This method can optionally be given a header from the file. This
1134 header will generally be the primary header or a merge of the first
1135 two headers.
1137 In the base class implementation it is assumed that
1138 this supplied header is the only useful header for metadata translation
1139 and it will be returned unchanged if given. This can avoid
1140 unnecessarily re-opening the file and re-reading the header when the
1141 content is already known.
1143 If no header is supplied, a header will be read from the supplied
1144 file using `~.file_helpers.read_basic_metadata_from_file`, allowing it
1145 to merge the primary and secondary header of a multi-extension FITS
1146 file. Subclasses can read the header from the data file using whatever
1147 technique is best for that instrument.
1149 Subclasses can return multiple headers and ignore the externally
1150 supplied header. They can also merge it with another header and return
1151 a new derived header if that is required by the particular data file.
1152 There is no requirement for the supplied header to be used.
1154 Parameters
1155 ----------
1156 filename : `str`
1157 Path to a file in a format understood by this translator.
1158 primary : `dict`-like, optional
1159 The primary header obtained by the caller. This is sometimes
1160 already known, for example if a system is trying to bootstrap
1161 without already knowing what data is in the file. For many
1162 instruments where the primary header is the only relevant
1163 header, the primary header will be returned with no further
1164 action.
1166 Yields
1167 ------
1168 headers : iterator of `dict`-like
1169 A header usable for metadata translation. For this base
1170 implementation it will be either the supplied primary header
1171 or a header read from the file. This implementation will only
1172 ever yield a single header.
1174 Notes
1175 -----
1176 Each translator class can have code specifically tailored to its
1177 own file format. It is important not to call this method with
1178 an incorrect translator class. The normal paradigm is for the
1179 caller to have read the first header and then called
1180 `determine_translator()` on the result to work out which translator
1181 class to then call to obtain the real headers to be used for
1182 translation.
1183 """
1184 if primary is not None:
1185 yield primary
1186 else:
1187 # Prevent circular import by deferring
1188 from .file_helpers import read_basic_metadata_from_file
1190 # Merge primary and secondary header if they exist.
1191 header = read_basic_metadata_from_file(filename, -1)
1192 assert header is not None # for mypy since can_raise=True
1193 yield header
1196def _make_abstract_translator_method(
1197 property: str, doc: str, return_typedoc: str, return_type: type
1198) -> Callable:
1199 """Create a an abstract translation method for this property.
1201 Parameters
1202 ----------
1203 property : `str`
1204 Name of the translator for property to be created.
1205 doc : `str`
1206 Description of the property.
1207 return_typedoc : `str`
1208 Type string of this property (used in the doc string).
1209 return_type : `type`
1210 Type of this property.
1212 Returns
1213 -------
1214 m : `~collections.abc.Callable`
1215 Translator method for this property.
1216 """
1218 def to_property(self: MetadataTranslator) -> None:
1219 raise NotImplementedError(f"Translator for '{property}' undefined.")
1221 to_property.__doc__ = f"""Return value of {property} from headers.
1223 {doc}
1225 Returns
1226 -------
1227 {property} : `{return_typedoc}`
1228 The translated property.
1229 """
1230 return to_property
1233# Make abstract methods for all the translators methods.
1234# Unfortunately registering them as abstractmethods does not work
1235# as these assignments come after the class has been created.
1236# Assigning to __abstractmethods__ directly does work but interacts
1237# poorly with the metaclass automatically generating methods from
1238# _trivialMap and _constMap.
1239# Note that subclasses that provide extension properties are assumed to not
1240# need abstract methods created for them.
1242# Allow for concrete translator methods to exist in the base class
1243# These translator methods can be defined in terms of other properties
1244CONCRETE = set()
1246for name, definition in PROPERTIES.items():
1247 method = f"to_{name}"
1248 if not MetadataTranslator.defined_in_this_class(method):
1249 setattr(
1250 MetadataTranslator,
1251 f"to_{name}",
1252 abstractmethod(
1253 _make_abstract_translator_method(
1254 name, definition.doc, definition.str_type, definition.py_type
1255 )
1256 ),
1257 )
1258 else:
1259 CONCRETE.add(method)
1262class StubTranslator(MetadataTranslator):
1263 """Translator where all the translations are stubbed out and issue
1264 warnings.
1266 This translator can be used as a base class whilst developing a new
1267 translator. It allows testing to proceed without being required to fully
1268 define all translation methods. Once complete the class should be
1269 removed from the inheritance tree.
1271 """
1273 pass
1276def _make_forwarded_stub_translator_method(
1277 cls: type[MetadataTranslator], property: str, doc: str, return_typedoc: str, return_type: type
1278) -> Callable:
1279 """Create a stub translation method for this property that calls the
1280 base method and catches `NotImplementedError`.
1282 Parameters
1283 ----------
1284 cls : `type`
1285 Class to use when referencing `super()`. This would usually be
1286 `StubTranslator`.
1287 property : `str`
1288 Name of the translator for property to be created.
1289 doc : `str`
1290 Description of the property.
1291 return_typedoc : `str`
1292 Type string of this property (used in the doc string).
1293 return_type : `type`
1294 Type of this property.
1296 Returns
1297 -------
1298 m : `~collections.abc.Callable`
1299 Stub translator method for this property.
1300 """
1301 method = f"to_{property}"
1303 def to_stub(self: MetadataTranslator) -> Any:
1304 parent = getattr(super(cls, self), method, None)
1305 try:
1306 if parent is not None:
1307 return parent()
1308 except NotImplementedError:
1309 pass
1311 warnings.warn(
1312 f"Please implement translator for property '{property}' for translator {self}", stacklevel=3
1313 )
1314 return None
1316 to_stub.__doc__ = f"""Unimplemented forwarding translator for {property}.
1318 {doc}
1320 Calls the base class translation method and if that fails with
1321 `NotImplementedError` issues a warning reminding the implementer to
1322 override this method.
1324 Returns
1325 -------
1326 {property} : `None` or `{return_typedoc}`
1327 Always returns `None`.
1328 """
1329 return to_stub
1332# Create stub translation methods for each property. These stubs warn
1333# rather than fail and should be overridden by translators.
1334for name, description in PROPERTIES.items():
1335 setattr(
1336 StubTranslator,
1337 f"to_{name}",
1338 _make_forwarded_stub_translator_method(
1339 StubTranslator, name, definition.doc, definition.str_type, definition.py_type # type: ignore
1340 ),
1341 )