Configuration

Data Directory

classy requires a directory where it can store data on your machine. The default location depends on your platform and system language. For English systems:

Platform	Directory
Linux	/home/$USER/.cache/classy
Mac	/Users/$USER/Library/Caches/classy
Windows	'C:\\Users\\$USER\\AppData\\Local\\classy\\Cache'

Multi-user friendly

The classy data directory can be shared between different devices and users. The filepaths of the spectra are stored relative to the data directory location.

You can change the location by setting the CLASSY_DATA_DIR environment variable.

Linux / MacOS

To set the environment variable once, use

$ export CLASSY_DATA_DIR=/path/to/your/data/directory

To make the change persistent, add the export command to the initialization file of your shell (e.g. .zshrc, .bashrc)

Windows

Start Menu -> Advanced System Settings -> Environment Variables

Extrapolation Limit

The extrapolation limit is applied when classifying spectra in the Tholen or the DeMeo taxonomy. If the covered wavelength range is within a given percentage of the required range, classy will apply constant extrapolation to cover the entire range and enable the classification. This limit can be set via classy.defs.EXTRAPOLATION_LIMIT and is 4.7 (=4.7%) by default, meaning that spectra covering 95.3% of the required wavelength range will be classified. This number was chosen as it just allows to classify Gaia DR3 spectra in the Tholen taxonomy.