# Licensed under a 3-clause BSD style license - see LICENSE.rst
import logging
import sys
import astropy.units as u
from astropy.coordinates import Angle, EarthLocation
from astropy.io 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 `~gammapy.data.Observation`,
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,
format=None,
):
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
self.format = format
[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 fits.open`
# because we don't want the file to remain open.
hdu_list = fits.open(str(filename), 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 gammapy.data import EventList
return EventList.read(filename, hdu=hdu)
elif hdu_class == "gti":
from gammapy.data import GTI
return GTI.read(filename, hdu=hdu)
elif hdu_class == "map":
from gammapy.maps import Map
return Map.read(filename, hdu=hdu, format=self.format)
else:
cls = IRF_REGISTRY.get_cls(hdu_class)
return cls.read(filename, 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):
self.name = name
def __get__(self, instance, objtype):
if instance is None:
# Accessed on a class, not an instance
return self
try:
return instance.__dict__[self.name]
except KeyError:
hdu_loc = instance.__dict__[f"_{self.name}_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__[self.name] = value
return value
def __set__(self, instance, value):
if isinstance(value, HDULocation):
instance.__dict__[f"_{self.name}_hdu"] = value
else:
instance.__dict__[self.name] = 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)
def earth_location_to_dict(location):
"""Create `~astropy.coordinates.EarthLocation` from FITS header dict."""
return {
"GEOLON": location.lon.deg,
"GEOLAT": location.lat.deg,
"ALTITUDE": location.height.to_value(u.m),
}