io.py 文件源码

def read_fits_healpix(filename):
    """
    Read the HEALPix map from a FITS file or a BinTableHDU to 1D array
    in *RING* ordering.

    Parameters
    ----------
    filename : str or `~astropy.io.fits.BinTableHDU`
        Filename of the HEALPix FITS file,
        or an `~astropy.io.fits.BinTableHDU` instance.

    Returns
    -------
    data : 1D `~numpy.ndarray`
        HEALPix data in *RING* ordering with same dtype as input
    header : `~astropy.io.fits.Header`
        Header of the input FITS file

    NOTE
    ----
    This function wraps on `healpy.read_map()`, but set the data type of
    data array to its original value as in FITS file, as well as return
    the header of input FITS file.
    """
    if isinstance(filename, fits.BinTableHDU):
        hdu = filename
    else:
        # Read the first extended table
        hdu = fits.open(filename)[1]
    # Hack to ignore the dtype byteorder, use native endianness
    dtype = np.dtype(hdu.data.field(0).dtype.type)
    header = hdu.header
    data = hp.read_map(hdu, nest=False, verbose=False)
    return (data.astype(dtype), header)