# Licensed under a 3-clause BSD style license - see LICENSE.rst
import pprint
from bs4 import BeautifulSoup
from urllib import parse as urlparse
from astropy import units as u
from . import conf
from ..query import BaseQuery
from ..utils import prepend_docstr_nosections, commons, async_to_sync
__doctest_skip__ = [
'SkyViewClass.get_images',
'SkyViewClass.get_images_async',
'SkyViewClass.get_image_list']
[docs]
@async_to_sync
class SkyViewClass(BaseQuery):
URL = conf.url
def __init__(self):
super().__init__()
self._default_form_values = None
def _get_default_form_values(self, form):
"""
Return the already selected values of a given form (a BeautifulSoup
form node) as a dict.
"""
res = []
for elem in form.find_all(['input', 'select']):
# ignore the submit and reset buttons
if elem.get('type') in ['submit', 'reset']:
continue
# check boxes: enabled boxes have the value "on" if not specified
# otherwise. Found out by debugging, perhaps not documented.
if (elem.get('type') == 'checkbox'
and elem.get('checked') in ["", "checked"]):
value = elem.get('value', 'on')
res.append((elem.get('name'), value))
# radio buttons and simple input fields
if elem.get('type') == 'radio' and\
elem.get('checked') in ["", "checked"] or\
elem.get('type') in [None, 'text']:
res.append((elem.get('name'), elem.get('value')))
# dropdown menu, multi-section possible
if elem.name == 'select':
for option in elem.find_all('option'):
if option.get('selected') == '':
value = option.get('value', option.text.strip())
res.append((elem.get('name'), value))
return {k: v
for (k, v) in res
if v not in [None, u'None', u'null'] and v
}
def _generate_payload(self, input=None):
"""
Fill out the form of the SkyView site and submit it with the
values given in ``input`` (a dictionary where the keys are the form
element's names and the values are their respective values).
"""
if input is None:
input = {}
form_response = self._request('GET', self.URL)
form_response.raise_for_status()
bs = BeautifulSoup(form_response.content, "html.parser")
form = bs.find('form')
# cache the default values to save HTTP traffic
if self._default_form_values is None:
self._default_form_values = self._get_default_form_values(form)
# only overwrite payload's values if the `input` value is not None
# to avoid overwriting of the form's default values
payload = self._default_form_values.copy()
for k, v in input.items():
if v is not None:
payload[k] = v
url = urlparse.urljoin(self.URL, form.get('action'))
return url, payload
def _submit_form(self, input=None, cache=True):
url, payload = self._generate_payload(input=input)
response = self._request('GET', url, params=payload, cache=cache)
response.raise_for_status()
return response
[docs]
def get_images(self, position, survey, *, coordinates=None, projection=None,
pixels=None, scaling=None, sampler=None, resolver=None,
deedger=None, lut=None, grid=None, gridlabels=None,
radius=None, height=None, width=None, cache=True,
show_progress=True):
"""
Query the SkyView service, download the FITS file that will be
found and return a generator over the local paths to the
downloaded FITS files.
Note that the files will be downloaded when the generator will be
exhausted, i.e. just calling this method alone without iterating
over the result won't issue a connection to the SkyView server.
Parameters
----------
position : str
Determines the center of the field to be retrieved. Both
coordinates (also equatorial ones) and object names are
supported. Object names are converted to coordinates via the
SIMBAD or NED name resolver. See the reference for more info
on the supported syntax for coordinates.
survey : str or list of str
Select data from one or more surveys. The number of surveys
determines the number of resulting file downloads. Passing a
list with just one string has the same effect as passing this
string directly.
coordinates : str
Choose among common equatorial, galactic and ecliptic
coordinate systems (``"J2000"``, ``"B1950"``, ``"Galactic"``,
``"E2000"``, ``"ICRS"``) or pass a custom string.
projection : str
Choose among the map projections (the value in parentheses
denotes the string to be passed):
Gnomonic (Tan), default value
good for small regions
Rectangular (Car)
simplest projection
Aitoff (Ait)
Hammer-Aitoff, equal area projection good for all sky maps
Orthographic (Sin)
Projection often used in interferometry
Zenith Equal Area (Zea)
equal area, azimuthal projection
COBE Spherical Cube (Csc)
Used in COBE data
Arc (Arc)
Similar to Zea but not equal-area
pixels : str
Selects the pixel dimensions of the image to be produced. A
scalar value or a pair of values separated by comma may be
given. If the value is a scalar the number of width and height
of the image will be the same. By default a 300x300 image is
produced.
scaling : str
Selects the transformation between pixel intensity and
intensity on the displayed image. The supported values are:
``"Log"``, ``"Sqrt"``, ``"Linear"``, ``"HistEq"``,
``"LogLog"``.
sampler : str
The sampling algorithm determines how the data requested will
be resampled so that it can be displayed.
resolver : str
The name resolver allows to choose a name resolver to use when
looking up a name which was passed in the ``position`` parameter
(as opposed to a numeric coordinate value). The default choice
is to call the SIMBAD name resolver first and then the NED
name resolver if the SIMBAD search fails.
deedger : str
When multiple input images with different backgrounds are
resampled the edges between the images may be apparent because
of the background shift. This parameter makes it possible to
attempt to minimize these edges by applying a de-edging
algorithm. The user can elect to choose the default given for
that survey, to turn de-edging off, or to use the default
de-edging algorithm. The supported values are: ``"_skip_"`` to
use the survey default, ``"skyview.process.Deedger"`` (for
enabling de-edging), and ``"null"`` to disable.
lut : str
Choose from the color table selections to display the data in
false color.
grid : bool
overlay a coordinate grid on the image if True
gridlabels : bool
annotate the grid with coordinates positions if True
radius : `~astropy.units.Quantity` or None
The angular radius of the specified field.
Overrides the ``width`` and ``height`` parameters.
width : `~astropy.units.Quantity` or None
The width of the specified field. Must be specified
with ``height``.
height : `~astropy.units.Quantity` or None
The height of the specified field. Must be specified
with ``width``.
cache : bool
Defaults to True. If set overrides global caching behavior.
See :ref:`caching documentation <astroquery_cache>`.
References
----------
.. [1] http://skyview.gsfc.nasa.gov/current/help/fields.html
Examples
--------
>>> sv = SkyView()
>>> paths = sv.get_images(position='Eta Carinae',
... survey=['Fermi 5', 'HRI', 'DSS'])
>>> for path in paths:
... print('\tnew file:', path)
Returns
-------
A list of `~astropy.io.fits.HDUList` objects.
"""
readable_objects = self.get_images_async(position, survey, coordinates=coordinates,
projection=projection, pixels=pixels, scaling=scaling,
sampler=sampler, resolver=resolver, deedger=deedger,
lut=lut, grid=grid, gridlabels=gridlabels,
radius=radius, height=height, width=width,
cache=cache, show_progress=show_progress)
return [obj.get_fits() for obj in readable_objects]
[docs]
@prepend_docstr_nosections(get_images.__doc__)
def get_images_async(self, position, survey, *, coordinates=None,
projection=None, pixels=None, scaling=None,
sampler=None, resolver=None, deedger=None, lut=None,
grid=None, gridlabels=None, radius=None, height=None,
width=None, cache=True, show_progress=True):
"""
Returns
-------
A list of context-managers that yield readable file-like objects
"""
image_urls = self.get_image_list(position, survey, coordinates=coordinates,
projection=projection, pixels=pixels, scaling=scaling, sampler=sampler,
resolver=resolver, deedger=deedger, lut=lut, grid=grid,
gridlabels=gridlabels, radius=radius,
height=height, width=width,
cache=cache)
return [commons.FileContainer(url, encoding='binary',
show_progress=show_progress)
for url in image_urls]
[docs]
@prepend_docstr_nosections(get_images.__doc__, sections=['Returns', 'Examples'])
def get_image_list(self, position, survey, *, coordinates=None,
projection=None, pixels=None, scaling=None,
sampler=None, resolver=None, deedger=None, lut=None,
grid=None, gridlabels=None, radius=None, width=None,
height=None, cache=True):
"""
Returns
-------
list of image urls
Examples
--------
>>> SkyView().get_image_list(position='Eta Carinae',
... survey=['Fermi 5', 'HRI', 'DSS'])
[u'http://skyview.gsfc.nasa.gov/tempspace/fits/skv6183161285798_1.fits',
u'http://skyview.gsfc.nasa.gov/tempspace/fits/skv6183161285798_2.fits',
u'http://skyview.gsfc.nasa.gov/tempspace/fits/skv6183161285798_3.fits']
"""
self._validate_surveys(survey)
if radius is not None:
size_deg = str(radius.to(u.deg).value * 2)
elif width is not None and height is not None:
size_deg = "{0},{1}".format(u.Quantity(width).to(u.deg).value,
u.Quantity(height).to(u.deg).value)
elif width is not None or height is not None:
raise ValueError("Must specify width and height if you "
"specify either.")
else:
size_deg = None
input = {
'Position': parse_coordinates(position),
'survey': survey,
'Deedger': deedger,
'lut': lut,
'projection': projection,
'gridlabels': '1' if gridlabels else '0',
'coordinates': coordinates,
'scaling': scaling,
'grid': grid,
'resolver': resolver,
'Sampler': sampler,
'imscale': size_deg,
'size': size_deg,
'pixels': pixels}
response = self._submit_form(input, cache=cache)
urls = self._parse_response(response)
return urls
def _parse_response(self, response):
bs = BeautifulSoup(response.content, "html.parser")
urls = []
for a in bs.find_all('a'):
if a.text == 'FITS':
href = a.get('href')
urls.append(urlparse.urljoin(response.url, href))
return urls
@property
def survey_dict(self):
if not hasattr(self, '_survey_dict'):
response = self._request('GET', self.URL, cache=False)
response.raise_for_status()
page = BeautifulSoup(response.content, "html.parser")
surveys = page.findAll('select', {'name': 'survey'})
self._survey_dict = {
sel['id']: [x.text for x in sel.findAll('option')]
for sel in surveys
if 'overlay' not in sel['id']
}
return self._survey_dict
@property
def _valid_surveys(self):
# Return a flat list of all valid surveys
return [x for v in self.survey_dict.values() for x in v]
def _validate_surveys(self, surveys):
if not isinstance(surveys, list):
surveys = [surveys]
for sv in surveys:
if sv not in self._valid_surveys:
raise ValueError("Survey is not among the surveys hosted "
"at skyview. See list_surveys or "
"survey_dict for valid surveys.")
[docs]
def list_surveys(self):
"""
Print out a formatted version of the survey dict
"""
pprint.pprint(self.survey_dict)
def parse_coordinates(position):
coord = commons.parse_coordinates(position)
return coord.fk5.to_string()
SkyView = SkyViewClass()