Source code for gammapy.utils.fits

# Licensed under a 3-clause BSD style license - see LICENSE.rst
import logging
import sys
from astropy.coordinates import Angle, EarthLocation
from import fits
from astropy.units import Quantity
from .scripts import make_path

log = logging.getLogger(__name__)

__all__ = ["earth_location_from_dict", "LazyFitsData", "HDULocation"]

[docs]class HDULocation: """HDU localisation, loading and Gammapy object mapper. This represents one row in `HDUIndexTable`. It's more a helper class, that is wrapped by ``, usually those objects will be used to access data. See also :ref:`gadf:hdu-index`. """ def __init__( self, hdu_class, base_dir=".", file_dir=None, file_name=None, hdu_name=None, cache=True, ): self.hdu_class = hdu_class self.base_dir = base_dir self.file_dir = file_dir self.file_name = file_name self.hdu_name = hdu_name self.cache = cache
[docs] def info(self, file=None): """Print some summary info to stdout.""" if not file: file = sys.stdout print(f"HDU_CLASS = {self.hdu_class}", file=file) print(f"BASE_DIR = {self.base_dir}", file=file) print(f"FILE_DIR = {self.file_dir}", file=file) print(f"FILE_NAME = {self.file_name}", file=file) print(f"HDU_NAME = {self.hdu_name}", file=file)
[docs] def path(self, abs_path=True): """Full filename path. Include ``base_dir`` if ``abs_path`` is True. """ path = make_path(self.base_dir) / self.file_dir / self.file_name if abs_path and path.exists(): return path else: return make_path(self.file_dir) / self.file_name
[docs] def get_hdu(self): """Get HDU.""" filename = self.path(abs_path=True) # Here we're intentionally not calling `with` # because we don't want the file to remain open. hdu_list =, memmap=False) return hdu_list[self.hdu_name]
[docs] def load(self): """Load HDU as appropriate class. TODO: this should probably go via an extensible registry. """ from gammapy.irf import IRF_REGISTRY hdu_class = self.hdu_class filename = self.path() hdu = self.hdu_name if hdu_class == "events": from import EventList return, hdu=hdu) elif hdu_class == "gti": from import GTI return, hdu=hdu) elif hdu_class == "map": from gammapy.maps import Map return, hdu=hdu) else: cls = IRF_REGISTRY.get_cls(hdu_class) return, hdu=hdu)
[docs]class LazyFitsData(object): """A lazy FITS data descriptor. Parameters ---------- cache : bool Whether to cache the data. """ def __init__(self, cache=True): self.cache = cache def __set_name__(self, owner, name): = name def __get__(self, instance, objtype): if instance is None: # Accessed on a class, not an instance return self try: return instance.__dict__[] except KeyError: hdu_loc = instance.__dict__[f"_{}_hdu"] try: value = hdu_loc.load() except KeyError: value = None log.warning(f"HDU '{hdu_loc.hdu_name}' not found") if self.cache and hdu_loc.cache: instance.__dict__[] = value return value def __set__(self, instance, value): if isinstance(value, HDULocation): instance.__dict__[f"_{}_hdu"] = value else: instance.__dict__[] = value
# TODO: add unit test
[docs]def earth_location_from_dict(meta): """Create `~astropy.coordinates.EarthLocation` from FITS header dict.""" lon = Angle(meta["GEOLON"], "deg") lat = Angle(meta["GEOLAT"], "deg") # TODO: should we support both here? # Check latest spec if ALTITUDE is used somewhere. if "GEOALT" in meta: height = Quantity(meta["GEOALT"], "meter") elif "ALTITUDE" in meta: height = Quantity(meta["ALTITUDE"], "meter") else: raise KeyError("The GEOALT or ALTITUDE header keyword must be set") return EarthLocation(lon=lon, lat=lat, height=height)