Python CCDData.to_hdu方法代码示例

# 需要导入模块: from astropy.nddata.ccddata import CCDData [as 别名]
# 或者: from astropy.nddata.ccddata.CCDData import to_hdu [as 别名]
def test_read_old_style_multiextensionfits(tmpdir):
    # Regression test for https://github.com/astropy/ccdproc/issues/664
    #
    # Prior to astropy 3.1 there was no uncertainty type saved
    # in the multiextension fits files generated by CCDData
    # because the uncertainty had to be StandardDevUncertainty.
    #
    # Current version should be able to read those in.
    #
    size = 4
    # Value of the variables below are not important to the test.
    data = np.zeros([size, size])
    mask = data > 0.9
    uncert = np.sqrt(data)

    ccd = CCDData(data=data, mask=mask, uncertainty=uncert, unit='adu')
    # We'll create the file manually to ensure we have the
    # right extension names and no uncertainty type.
    hdulist = ccd.to_hdu()
    del hdulist[2].header['UTYPE']
    file_name = tmpdir.join('old_ccddata_mef.fits').strpath
    hdulist.writeto(file_name)

    ccd = CCDData.read(file_name)

    assert isinstance(ccd.uncertainty, StdDevUncertainty)

# 需要导入模块: from astropy.nddata.ccddata import CCDData [as 别名]
# 或者: from astropy.nddata.ccddata.CCDData import to_hdu [as 别名]
def test_wcs_attribute(ccd_data, tmpdir):
    """
    Check that WCS attribute gets added to header, and that if a CCDData
    object is created from a FITS file with a header, and the WCS attribute
    is modified, then the CCDData object is turned back into an hdu, the
    WCS object overwrites the old WCS information in the header.
    """
    tmpfile = tmpdir.join('temp.fits')
    # This wcs example is taken from the astropy.wcs docs.
    wcs = WCS(naxis=2)
    wcs.wcs.crpix = np.array(ccd_data.shape) / 2
    wcs.wcs.cdelt = np.array([-0.066667, 0.066667])
    wcs.wcs.crval = [0, -90]
    wcs.wcs.ctype = ["RA---AIR", "DEC--AIR"]
    wcs.wcs.set_pv([(2, 1, 45.0)])
    ccd_data.header = ccd_data.to_hdu()[0].header
    ccd_data.header.extend(wcs.to_header(), useblanks=False)
    ccd_data.write(tmpfile.strpath)

    # Get the header length after it has been extended by the WCS keywords
    original_header_length = len(ccd_data.header)

    ccd_new = CCDData.read(tmpfile.strpath)
    # WCS attribute should be set for ccd_new
    assert ccd_new.wcs is not None
    # WCS attribute should be equal to wcs above.
    assert ccd_new.wcs.wcs == wcs.wcs

    # Converting CCDData object with wcs to an hdu shouldn't
    # create duplicate wcs-related entries in the header.
    ccd_new_hdu = ccd_new.to_hdu()[0]
    assert len(ccd_new_hdu.header) == original_header_length

    # Making a CCDData with WCS (but not WCS in the header) should lead to
    # WCS information in the header when it is converted to an HDU.
    ccd_wcs_not_in_header = CCDData(ccd_data.data, wcs=wcs, unit="adu")
    hdu = ccd_wcs_not_in_header.to_hdu()[0]
    wcs_header = wcs.to_header()
    for k in wcs_header.keys():
        # Skip these keywords if they are in the WCS header because they are
        # not WCS-specific.
        if k in ['', 'COMMENT', 'HISTORY']:
            continue
        # No keyword from the WCS should be in the header.
        assert k not in ccd_wcs_not_in_header.header
        # Every keyword in the WCS should be in the header of the HDU
        assert hdu.header[k] == wcs_header[k]

    # Now check that if WCS of a CCDData is modified, then the CCDData is
    # converted to an HDU, the WCS keywords in the header are overwritten
    # with the appropriate keywords from the header.
    #
    # ccd_new has a WCS and WCS keywords in the header, so try modifying
    # the WCS.
    ccd_new.wcs.wcs.cdelt *= 2
    ccd_new_hdu_mod_wcs = ccd_new.to_hdu()[0]
    assert ccd_new_hdu_mod_wcs.header['CDELT1'] == ccd_new.wcs.wcs.cdelt[0]
    assert ccd_new_hdu_mod_wcs.header['CDELT2'] == ccd_new.wcs.wcs.cdelt[1]