**************************** Getting Started with Astropy **************************** Importing Astropy ================= In order to encourage consistency amongst users in importing and using Astropy functionality, we have put together the following guidelines. Since most of the functionality in Astropy resides in sub-packages, importing astropy as:: >>> import astropy is not very useful. Instead, it is best to import the desired sub-pacakge with the syntax:: >>> from astropy import subpackage For example, to access the FITS-related functionality, you can import `astropy.io.fits` with:: >>> from astropy.io import fits >>> hdulist = fits.open('data.fits') In specific cases, we have recommended shortcuts in the documentation for specific sub-packages, for example:: >>> from astropy import units as u >>> from astropy import coordinates as coord >>> coord.ICRSCoordinates(ra=10.68458, dec=41.26917, unit=(u.degree, u.degree))) Finally, in some cases, most of the required functionality is contained in a single class (or a few classes). In those cases, the class can be directly imported:: >>> from astropy.cosmology import WMAP7 >>> from astropy.table import Table >>> from astropy.wcs import WCS Note that for clarity, and to avoid any issues, we recommend to **never** import any Astropy functionality using ``*``, for example:: >>> from astropy.io.fits import * # NOT recommended Some components of Astropy started off as standalone packages (e.g. PyFITS, PyWCS), so in cases where Astropy needs to be used as a drop-in replacement, the following syntax is also acceptable:: >>> from astropy.io import fits as pyfits