CoSpecPy 0.3

Python Package for SDSS Composite Spectra

CoSpecPy - SDSS Composites Made Easy

This is a package written for the purpose of creating composite spectra from SDSS data releases.

Future releases will contain additional features for plotting and uncertainty information. Connections to astropy Tables and queries are also a possibility.

Install Instructions

Install using pip available through:

pip install CoSpecPy

Or alternatively you can clone this GitHub repository, navigate to the directory you have just cloned and run:

python setup.py install

Quick Start

The only feature currently implemented (Day 1) is the DownloadHandler and the basics of the main Composite class. Make sure that either wget or aria2 is installed on your machine.

For a quick example you can use

from CoSpecPy import DownloadHandler, Composite # Import the Handler

example_handler = DownloadHandler(download_method = "wget", #Download method (aria2 or wget)
no_of_connections = 1, batch_size="10", #Connections only apply to aria2, batches not implemented
 download_folder="/path/to/output") # output folder

#Example download with wget
example_handler.download_example()

#This will download the 25 example spectra in CoSpecPy/data/example_speclist.txt to your chosen output

example_composite = Composite(name = "example_composite") #Creation of Composite Class
example_composite.example_from_downloads() # Will add various parameters and plot the 25 spectra

Output should look something like this

Download Dependencies

The DownloadHandler requires use of either wget or aria2 to download from the SDSS servers.

wget is GNU Wget is a free software package for retrieving files using HTTP, HTTPS, FTP and FTPS. Information and documentation can be found here https://www.gnu.org/software/wget/. For a quick Debian/Ubuntu install try:

sudo apt-get install wget

aria2 is a lightweight multi-protocol & multi-source command-line download utility. Information and documentation can be found here https://aria2.github.io/. For a quick Debian/Ubuntu install try:

sudo apt-get install -y aria2

Features Implemented

Download of spectra list using either aria2 or wget. aria2 allows for easy opening of multiple connections for a much faster download.

Example included with DownloadHandler.download_example()

Future Features

• Batch-split downloads given spectra list
• Spectral composite making from downloads - Options for wavelength grid, normalisation range, uncertainty estimation, plotting
• Helper functions to go from an astropy.Table through to composite making
• Possible inclusion of SDSS querying to create the fetch information for speclist
• Long-term, add external features such as redenning estimation