def create_from_hdu(cls, hdu, ebins):
        """ Creates and returns an HpxMap object from a FITS HDU.

        hdu    : The FITS
        ebins  : Energy bin edges [optional]
        """
        hpx = HPX.create_from_hdu(hdu, ebins)
        colnames = hdu.columns.names
        cnames = []
        if hpx.conv.convname == 'FGST_SRCMAP_SPARSE':
            pixs = hdu.data.field('PIX')
            chans = hdu.data.field('CHANNEL')
            keys = chans * hpx.npix + pixs
            vals = hdu.data.field('VALUE')
            nebin = len(ebins)
            data = np.zeros((nebin, hpx.npix))
            data.flat[keys] = vals
        else:
            for c in colnames:
                if c.find(hpx.conv.colstring) == 0:
                    cnames.append(c)
            nebin = len(cnames)
            data = np.ndarray((nebin, hpx.npix))
            for i, cname in enumerate(cnames):
                data[i, 0:] = hdu.data.field(cname)

        return cls(data, hpx)
Creates and returns an HpxMap object from a FITS HDU.

        hdu    : The FITS
        ebins  : Energy bin edges [optional]