Introduction to tree

The SAS Tree defines the directory structure in which all SDSS data files live. The SAS tree product helps set up all the SDSS environment variables you need to run SDSS products. The list of currrently available environment variables can be found here.

This product provides a Python package version of the tree. See the installation instructions. To use the tree, and set up its environment variables, you may simply import it:

# import the tree
from tree import Tree

# plant a new tree
my_tree = Tree()

When you plant a new tree, the first thing it tries to do is set a TREE_DIR and SAS_BASE_DIR environment variable. Tree always first checks for already-defined environment variables in the users environment, and uses those if found. Otherwise it sets default locations for TREE_DIR and SAS_BASE_DIR. The default location for TREE_DIR will be the location of the installed package. The default location for SAS_BASE_DIR will be a new sas directory in the users home directory. By default, it will load all the paths set within the sdsswork configuration and populate your local Python environment, os.environ, if they are not currently found.

To only load a subset of environment variables, use the key keyword argument.

# only load MaNGA environment variables
my_tree = Tree(key='manga')

# load MaNGA and eBOSS
my_tree = Tree(key=['eboss', 'manga'])

The environment variables for the specified keys are now loaded into your Python os environment:

import os
os.environ['MANGA_SPECTRO_REDUX']

You can load a new section into an existing tree with add_limbs:

# adds the APO tree section into your os environment
my_tree.add_limbs(key='apo')

You can load a tree with a different configuration.

dr15_tree = Tree(config='dr15')

Instantiating a tree in this way will not overwrite any existing, or prior set, environment variables. To update existing tree environment variables after loading one configuration within the same session, you can use replant_tree:

# load the default tree
my_tree = Tree()

# switch to the dr15 tree
my_tree.replant_tree(config='dr15')

To see what configs are available to load with Tree, use the list_available_configs method.

my_tree = Tree()
my_tree.list_available_configs()
['bosswork.cfg', 'dr7.cfg', 'dr8.cfg', 'dr9.cfg', 'dr10.cfg', 'dr11.cfg', 'dr12.cfg',
'dr13.cfg', 'dr14.cfg', 'dr15.cfg', 'dr16.cfg', 'mpl9.cfg', 'sdss5.cfg', 'sdsswork.cfg']

To see the available data releases, use the get_available_releases method. This will return a list of all public Data Release (DR) versions along with any additional survey versions, e.g. MaNGA’s MPLs. Any config files that end with work get combined into a single work release.

my_tree = Tree()
my_tree.get_available_releases()
['WORK', 'DR7', 'DR8', 'DR9', 'DR10', 'DR11', 'DR12', 'DR13', 'DR14', 'DR15', 'DR16']

# return only the public data releases
my_tree.get_available_releases(public=True)
['DR7', 'DR8', 'DR9', 'DR10', 'DR11', 'DR12', 'DR13', 'DR14', 'DR15', 'DR16']

Reference/API

Class

tree.Tree([config, key, uproot_with, …])

Initialize the sdss tree object

Methods

tree.Tree.add_limbs([key])	Add a new section from the tree into the existing os environment
tree.Tree.list_keys()	List the available keys you can load
tree.Tree.replant_tree([config, exclude])	Replant the tree with a different config setup