# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This module provides tools for loading example datasets, from both
within photutils and remote servers.
"""
from urllib.error import HTTPError, URLError
from astropy.io import fits
from astropy.table import Table
from astropy.utils.data import download_file, get_pkg_data_filename
__all__ = [
'get_path',
'load_irac_psf',
'load_simulated_hst_star_image',
'load_spitzer_catalog',
'load_spitzer_image',
'load_star_image',
]
[docs]
def get_path(filename, location='local', cache=True, show_progress=False):
"""
Get the local path for a given file.
Parameters
----------
filename : str
File name in the local or remote data folder.
location : {'local', 'remote', 'photutils-datasets'}
File location. ``'local'`` means bundled with ``photutils``.
``'remote'`` means the astropy data server (or the
photutils-datasets repo as a backup) or the Astropy cache
on your machine. ``'photutils-datasets'`` means the
photutils-datasets repo or the Astropy cache on your machine.
cache : bool, optional
Whether to cache the contents of remote URLs. Default is `True`.
show_progress : bool, optional
Whether to display a progress bar during the download (default
is `False`). The progress bar is displayed only when outputting
to a terminal.
Returns
-------
path : str
The local path of the file.
"""
datasets_url = ('https://github.com/astropy/photutils-datasets/raw/'
f'main/data/{filename}')
if location == 'local':
path = get_pkg_data_filename('data/' + filename)
elif location == 'remote': # pragma: no cover
try:
url = f'https://data.astropy.org/photometry/{filename}'
path = download_file(url, cache=cache,
show_progress=show_progress)
except (URLError, HTTPError): # timeout or not found
path = download_file(datasets_url, cache=cache,
show_progress=show_progress)
elif location == 'photutils-datasets': # pragma: no cover
path = download_file(datasets_url, cache=cache,
show_progress=show_progress)
else:
raise ValueError(f'Invalid location: {location}')
return path
[docs]
def load_spitzer_image(show_progress=False): # pragma: no cover
"""
Load a 4.5 micron Spitzer image.
The catalog for this image is returned by
:func:`load_spitzer_catalog`.
Parameters
----------
show_progress : bool, optional
Whether to display a progress bar during the download (default
is `False`).
Returns
-------
hdu : `~astropy.io.fits.ImageHDU`
The 4.5 micron Spitzer image in a FITS image HDU.
See Also
--------
load_spitzer_catalog
Examples
--------
.. plot::
:include-source:
import matplotlib.pyplot as plt
from photutils.datasets import load_spitzer_image
hdu = load_spitzer_image()
plt.imshow(hdu.data, origin='lower', vmax=50)
"""
path = get_path('spitzer_example_image.fits', location='remote',
show_progress=show_progress)
with fits.open(path) as hdulist:
data = hdulist[0].data
header = hdulist[0].header
return fits.ImageHDU(data, header)
[docs]
def load_spitzer_catalog(show_progress=False): # pragma: no cover
"""
Load a 4.5 micron Spitzer catalog.
The image from which this catalog was derived is returned by
:func:`load_spitzer_image`.
Parameters
----------
show_progress : bool, optional
Whether to display a progress bar during the download (default
is `False`).
Returns
-------
catalog : `~astropy.table.Table`
The catalog of sources.
See Also
--------
load_spitzer_image
Examples
--------
.. plot::
:include-source:
import matplotlib.pyplot as plt
from photutils.datasets import load_spitzer_catalog
catalog = load_spitzer_catalog()
plt.scatter(catalog['l'], catalog['b'])
plt.xlabel('Galactic l')
plt.ylabel('Galactic b')
plt.xlim(18.39, 18.05)
plt.ylim(0.13, 0.30)
"""
path = get_path('spitzer_example_catalog.xml', location='remote',
show_progress=show_progress)
return Table.read(path)
[docs]
def load_irac_psf(channel, show_progress=False): # pragma: no cover
"""
Load a Spitzer IRAC PSF image.
Parameters
----------
channel : int (1-4)
The IRAC channel number:
* Channel 1: 3.6 microns
* Channel 2: 4.5 microns
* Channel 3: 5.8 microns
* Channel 4: 8.0 microns
show_progress : bool, optional
Whether to display a progress bar during the download (default
is `False`).
Returns
-------
hdu : `~astropy.io.fits.ImageHDU`
The IRAC PSF in a FITS image HDU.
Examples
--------
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.visualization import ImageNormalize, LogStretch
from photutils.datasets import load_irac_psf
hdu1 = load_irac_psf(1)
hdu2 = load_irac_psf(2)
hdu3 = load_irac_psf(3)
hdu4 = load_irac_psf(4)
norm = ImageNormalize(hdu1.data, stretch=LogStretch())
fig, ((ax1, ax2), (ax3, ax4)) = plt.subplots(2, 2)
ax1.imshow(hdu1.data, origin='lower', interpolation='nearest',
norm=norm)
ax1.set_title('IRAC Ch1 PSF')
ax2.imshow(hdu2.data, origin='lower', interpolation='nearest',
norm=norm)
ax2.set_title('IRAC Ch2 PSF')
ax3.imshow(hdu3.data, origin='lower', interpolation='nearest',
norm=norm)
ax3.set_title('IRAC Ch3 PSF')
ax4.imshow(hdu4.data, origin='lower', interpolation='nearest',
norm=norm)
ax4.set_title('IRAC Ch4 PSF')
plt.tight_layout()
plt.show()
"""
channel = int(channel)
if channel < 1 or channel > 4:
raise ValueError('channel must be 1, 2, 3, or 4')
filepath = f'irac_ch{channel}_flight.fits'
path = get_path(filepath, location='remote', show_progress=show_progress)
with fits.open(path) as hdulist:
data = hdulist[0].data
header = hdulist[0].header
return fits.ImageHDU(data, header)
[docs]
def load_star_image(show_progress=False): # pragma: no cover
"""
Load an optical image of stars.
This is an image of M67 from photographic data obtained as part of
the National Geographic Society - Palomar Observatory Sky Survey
(NGS-POSS). The image was digitized from the POSS-I Red plates as
part of the Digitized Sky Survey produced at the Space Telescope
Science Institute.
Parameters
----------
show_progress : bool, optional
Whether to display a progress bar during the download (default
is `False`).
Returns
-------
hdu : `~astropy.io.fits.ImageHDU`
The M67 image in a FITS image HDU.
Examples
--------
.. plot::
:include-source:
import matplotlib.pyplot as plt
from photutils.datasets import load_star_image
hdu = load_star_image()
plt.imshow(hdu.data, origin='lower', interpolation='nearest')
"""
path = get_path('M6707HH.fits', location='remote',
show_progress=show_progress)
with fits.open(path) as hdulist:
data = hdulist[0].data
header = hdulist[0].header
return fits.ImageHDU(data, header)
[docs]
def load_simulated_hst_star_image(show_progress=False): # pragma: no cover
"""
Load a simulated HST WFC3/IR F160W image of stars.
The simulated image does not contain any background or noise.
Parameters
----------
show_progress : bool, optional
Whether to display a progress bar during the download (default
is `False`).
Returns
-------
hdu : `~astropy.io.fits.ImageHDU`
A FITS image HDU containing the simulated HST star image.
Examples
--------
.. plot::
:include-source:
import matplotlib.pyplot as plt
from photutils.datasets import load_simulated_hst_star_image
hdu = load_simulated_hst_star_image()
plt.imshow(hdu.data, origin='lower', interpolation='nearest')
"""
path = get_path('hst_wfc3ir_f160w_simulated_starfield.fits',
location='photutils-datasets',
show_progress=show_progress)
with fits.open(path) as hdulist:
data = hdulist[0].data
header = hdulist[0].header
return fits.ImageHDU(data, header)
