Introduction to sdss_access¶

Path Generation¶

You can generate full paths to files easily with Path.full:

# import the path
from sdss_access import SDSSPath
path = SDSSPath()

# generate a file system path
path.full('mangacube', drpver='v2_3_1', plate='8485', ifu='1901')
'/Users/Brian/Work/sdss/sas/mangawork/manga/spectro/redux/v2_3_1/8485/stack/manga-8485-1902-LOGCUBE.fits.gz'

Note that this only generates a path. The file may not actually exist locally. If you want to generate a URL path to the file at Utah, you can use Path.url:

# generate a http path to the file
path.url('mangacube', drpver='v2_3_1', plate='8485', ifu='1901')
'https://data.sdss.org/sas/mangawork/manga/spectro/redux/v2_3_1/8485/stack/manga-8485-1902-LOGCUBE.fits.gz'

Path Names¶

The syntax for all paths defined in sdss_access, for most methods, is (name, **kwargs). Each path is defined by a name and several keyword arguments, indicated in the template filepath by {keyword_name}. For example, the path to a MaNGA data cube has name mangacube and path keywords, plate, drpver, and ifu, defined in the path $MANGA_SPECTRO_REDUX/{drpver}/{plate}/stack/manga-{plate}-{ifu}-LOGCUBE.fits.gz. All paths are defined inside the SDSS tree product, within the sdss_paths.ini file, and available to you as a dictionary, path.templates:

from sdss_access import SDSSPath
path = SDSSPath()

# show the dictionary of available paths
path.templates

To look up what keywords are needed for a given path, you can use path.lookup_keys:

# look up the keyword arguments needed to define a MaNGA cube path
path.lookup_keys('mangacube')
['plate', 'drpver', 'ifu']

The full list of paths can also be found here.

Downloading Files¶

You can download files from the SAS and place them in your local SAS. sdss_access expects a local SAS filesystem that mimics the real SAS at Utah. If you do not already have a SAS_BASE_DIR set, one will be defined in your home directory, as a new sas directory.

Using the HttpAccess package.

from sdss_access import HttpAccess
http_access = HttpAccess(verbose=True)

# set to use remote
http_access.remote()

# get th file
http_access.get('mangacube', drpver='v2_3_1', plate='8485', ifu='1901')

Using the RsyncAccess package. RsyncAccess is generally much faster then HttpAccess as it spreads multiple file downloads across multiple continuous rsync download streams.

# import the rsync package
from sdss_access import RsyncAccess
rsync = RsyncAccess()

# sets a remote mode to the real SAS
rsync.remote()

# add all the file(s) you want to download
# let's download all MPL-6 MaNGA cubes for plate 8485
rsync.add('mangacube', drpver='v2_3_1', plate='8485', ifu='*')

# set the stream tasks
rsync.set_stream()

# start the download(s)
rsync.commit()

Reference/API¶

Class

Methods