Dataset access (
gammapy.datasets contains function to easily access datasets that are
relevant for gamma-ray astronomy.
The functions have a naming pattern (following the
load_*functions load datasets that are distributed with Gammapy (bundled in the repo)
fetch_*functions fetch datasets from the web (either from
gammapy-extraor other sites)
make_*functions create datasets programatically (sometimes involving a random number generator)
To keep the Gammapy code repository at https://github.com/gammapy/gammapy small and clean, we are putting sample data files and IPython notebooks in an extra repository at https://github.com/gammapy/gammapy-extra/ .
To get the repository,
git clone it to a location of your choosing using a git protocol of your choosing
(try HTTPS or see the Github clone URL help article if you’re not sure which you want).
git clone https://github.com/gammapy/gammapy-extra.git git clone email@example.com:gammapy/gammapy-extra.git
If you don’t have git, you can also fetch the latest version as a zip file:
wget https://github.com/gammapy/gammapy-extra/archive/master.zip unzip master.zip # will result in a `gammapy-extra-master` folder
The Gammapy tests, docs generator, examples and tutorials will access files from the
repo using the
For this to work, you have to set the
GAMMAPY_EXTRA shell environment variable to point to that folder.
We suggest you put this in you
After you’ve done this, open up a new terminal (or
source .profile) and check if
gammapy-extra is found:
# TODO: make this print some info about gammapy-extra (including a version!!!) gammapy info
>>> from gammapy.datasets import gammapy_extra >>> gammapy_extra.filename('logo/gammapy_banner.png') '/Users/deil/code/gammapy-extra/logo/gammapy_banner.png'
Gamma-cat is an open catalog for TeV gamma-ray sources. It is maintained as an
open git repository and hosted on github. To get the data you can use the
git clone command:
git clone https://github.com/gammapy/gamma-cat.git git clone firstname.lastname@example.org:gammapy/gamma-cat.git
If you don’t have git, you can also fetch the latest version as a zip file as well:
wget https://github.com/gammapy/gamma-cat/archive/master.zip unzip master.zip # will result in a `gamma-cat-master` folder
classes need to know where the gamma-cat repository is located on your machine.
For this reason the
GAMMA_CAT shell environment variable has to be set using:
Example how to load a dataset that is distributed with the code
gammapy repo (i.e. will be available even if you’re offline)
>>> from gammapy.datasets import load_crab_flux_points >>> flux_points = load_crab_flux_points()
Example how to fetch a dataset from the web (i.e. will download to the Astropy cache and need internet access on first call):
>>> from gammapy.datasets import fetch_fermi_diffuse_background_model >>> catalog = fetch_fermi_diffuse_background_model()
TODO: explain how the Astropy cache works and make it configurable for Gammapy.
Example how to make a dataset (from scratch, no file is loaded):
>>> from gammapy.datasets import make_test_psf >>> psf = make_test_psf(energy_bins=20)
||Load published Crab pulsar and nebula flux points.|
||Load published diffuse gamma-ray spectrum.|
||Load published electron spectrum.|
||Load Poisson statistics counts image of a Gaussian source on flat background.|
||Load published TeV flux point measurements.|
||Download and access for all built-in datasets.|
||Fermi high-energy data for the Galactic center region.|
||Fermi dataset container class, with lazy data access.|