Python fits.extract_waveunit函数代码示例

def test_extract_waveunit_wavelnthcomment_parentheses():
    # WAVELNTH comment is: "Observed wavelength (nm)"
    waveunit = extract_waveunit(get_header(SVSM_IMAGE)[0])
    assert waveunit == 'nm'

def entries_from_file(file, default_waveunit=None):
    """Use the headers of a FITS file to generate an iterator of
    :class:`sunpy.database.tables.DatabaseEntry` instances. Gathered
    information will be saved in the attribute `fits_header_entries`. If the
    key INSTRUME, WAVELNTH or DATE-OBS / DATE_OBS is available, the attribute
    `instrument`, `wavemin` and `wavemax` or `observation_time_start` is set,
    respectively. If the wavelength unit can be read, the values of `wavemin`
    and `wavemax` are converted to nm (nanometres). The value of the `file`
    parameter is used to set the attribute `path` of each generated database
    entry.

    Parameters
    ----------
    file : str or file-like object
        Either a path pointing to a FITS file or a an opened file-like object.
        If an opened file object, its mode must be one of the following rb,
        rb+, or ab+.

    default_waveunit : str, optional
        The wavelength unit that is used for a header if it cannot be
        found.

    Raises
    ------
    sunpy.database.WaveunitNotFoundError
        If `default_waveunit` is not given and the wavelength unit cannot
        be found in one of the FITS headers

    sunpy.WaveunitNotConvertibleError
        If a wavelength unit could be found but cannot be used to create an
        instance of the type ``astropy.units.Unit``. This can be the case
        for example if a FITS header has the key `WAVEUNIT` with the value
        `nonsense`.

    Examples
    --------
    >>> entries = list(entries_from_file(sunpy.data.sample.SWAP_LEVEL1_IMAGE))
    >>> len(entries)
    1
    >>> entry = entries.pop()
    >>> entry.instrument
    'SWAP'
    >>> entry.observation_time_start, entry.observation_time_end
    (datetime.datetime(2012, 1, 1, 0, 16, 7, 836000), None)
    >>> entry.wavemin, entry.wavemax
    (17.400000000000002, 17.400000000000002)
    >>> len(entry.fits_header_entries)
    112

    """
    headers = fits.get_header(file)
    if isinstance(file, (str, unicode)):
        filename = file
    else:
        filename = getattr(file, "name", None)
    for header in headers:
        entry = DatabaseEntry(path=filename)
        for key, value in header.iteritems():
            # Yes, it is possible to have an empty key in a FITS file.
            # Example: sunpy.data.sample.EIT_195_IMAGE
            # Don't ask me why this could be a good idea.
            if key == "":
                value = str(value)
            elif key == "KEYCOMMENTS":
                for k, v in value.iteritems():
                    entry.fits_key_comments.append(FitsKeyComment(k, v))
                continue
            entry.fits_header_entries.append(FitsHeaderEntry(key, value))
        waveunit = fits.extract_waveunit(header)
        if waveunit is None:
            waveunit = default_waveunit
        unit = None
        if waveunit is not None:
            try:
                unit = Unit(waveunit)
            except ValueError:
                raise WaveunitNotConvertibleError(waveunit)
        for header_entry in entry.fits_header_entries:
            key, value = header_entry.key, header_entry.value
            if key == "INSTRUME":
                entry.instrument = value
            elif key == "WAVELNTH":
                if unit is None:
                    raise WaveunitNotFoundError(file)
                # use the value of `unit` to convert the wavelength to nm
                entry.wavemin = entry.wavemax = unit.to(nm, value, equivalencies.spectral())
            # NOTE: the key DATE-END or DATE_END is not part of the official
            # FITS standard, but many FITS files use it in their header
            elif key in ("DATE-END", "DATE_END"):
                entry.observation_time_end = parse_time(value)
            elif key in ("DATE-OBS", "DATE_OBS"):
                entry.observation_time_start = parse_time(value)
        yield entry

def test_extract_waveunit_waveunitcomment():
    # comment of WAVEUNIT is: "in meters"
    waveunit = extract_waveunit(get_header(NA_IMAGE)[0])
    assert waveunit == 'm'

def test_extract_waveunit_wavelnthcomment_brackets():
    # WAVELNTH comment is: "[Angstrom] bandpass peak response"
    waveunit = extract_waveunit(get_header(SWAP_LEVEL1_IMAGE)[0])
    assert waveunit == 'angstrom'

def test_extract_waveunit_minus9():
    # value of WAVEUNIT is -9
    waveunit = extract_waveunit(get_header(MEDN_IMAGE)[0])
    assert waveunit == 'nm'

def test_extract_waveunit_minus10():
    # value of WAVEUNIT is -10
    waveunit = extract_waveunit(get_header(MQ_IMAGE)[0])
    assert waveunit == 'angstrom'

def test_missing_waveunit_in_wavelnth_comment():
    # the comment of the key WAVELNTH has the value
    # '171 = Fe IX/X, 195 = Fe XII,' which contains no unit information
    waveunit = extract_waveunit(get_header(EIT_195_IMAGE)[0])
    assert waveunit is None

def test_extract_waveunit_from_waveunit_key():
    # the key WAVEUNIT can be accessed and returned directly
    waveunit = extract_waveunit(get_header(AIA_171_IMAGE)[0])
    assert waveunit == 'angstrom'

def test_extract_waveunit_missing_waveunit_key_and_missing_wavelnth_comment():
    waveunit = extract_waveunit(get_header(RHESSI_IMAGE)[0])
    assert waveunit is None

def test_extract_waveunit_wavelnthcomment_parentheses():
    # WAVELNTH comment is: "Observed wavelength (nm)"
    with pytest.warns(AstropyUserWarning, match='File may have been truncated'):
        waveunit = extract_waveunit(get_header(SVSM_IMAGE)[0])
    assert waveunit == 'nm'

def test_extract_waveunit_waveunitcomment():
    # comment of WAVEUNIT is: "in meters"
    with pytest.warns(AstropyUserWarning, match='File may have been truncated'):
        waveunit = extract_waveunit(get_header(NA_IMAGE)[0])
    assert waveunit == 'm'

def test_extract_waveunit_minus10():
    # value of WAVEUNIT is -10
    with pytest.warns(AstropyUserWarning, match='File may have been truncated'):
        waveunit = extract_waveunit(get_header(MQ_IMAGE)[0])
    assert waveunit == 'angstrom'

def entries_from_file(file, default_waveunit=None,
                      time_string_parse_format=''):
    # Note: time_string_parse_format='' so that None won't be passed to Time.strptime
    # (which would make strptime freak out, if I remember correctly).
    """Use the headers of a FITS file to generate an iterator of
    :class:`sunpy.database.tables.DatabaseEntry` instances. Gathered
    information will be saved in the attribute `fits_header_entries`. If the
    key INSTRUME, WAVELNTH or DATE-OBS / DATE_OBS is available, the attribute
    `instrument`, `wavemin` and `wavemax` or `observation_time_start` is set,
    respectively. If the wavelength unit can be read, the values of `wavemin`
    and `wavemax` are converted to nm (nanometres). The value of the `file`
    parameter is used to set the attribute `path` of each generated database
    entry.

    Parameters
    ----------
    file : str or file-like object
        Either a path pointing to a FITS file or a an opened file-like object.
        If an opened file object, its mode must be one of the following rb,
        rb+, or ab+.

    default_waveunit : str, optional
        The wavelength unit that is used for a header if it cannot be
        found.

    time_string_parse_format : str, optional
        Fallback timestamp format which will be passed to
        `~astropy.time.Time.strptime` if `sunpy.time.parse_time` is unable to
        automatically read the `date-obs` metadata.

    Raises
    ------
    sunpy.database.WaveunitNotFoundError
        If `default_waveunit` is not given and the wavelength unit cannot
        be found in one of the FITS headers

    sunpy.WaveunitNotConvertibleError
        If a wavelength unit could be found but cannot be used to create an
        instance of the type ``astropy.units.Unit``. This can be the case
        for example if a FITS header has the key `WAVEUNIT` with the value
        `nonsense`.

    Examples
    --------
    >>> from sunpy.database.tables import entries_from_file
    >>> import sunpy.data.sample  # doctest: +REMOTE_DATA
    >>> entries = list(entries_from_file(sunpy.data.sample.SWAP_LEVEL1_IMAGE))  # doctest: +REMOTE_DATA
    >>> len(entries)  # doctest: +REMOTE_DATA
    1
    >>> entry = entries.pop()  # doctest: +REMOTE_DATA
    >>> entry.instrument  # doctest: +REMOTE_DATA
    'SWAP'
    >>> entry.observation_time_start, entry.observation_time_end  # doctest: +REMOTE_DATA
    (datetime.datetime(2011, 6, 7, 6, 33, 29, 759000), None)
    >>> entry.wavemin, entry.wavemax  # doctest: +REMOTE_DATA
    (17.400000000000002, 17.400000000000002)
    >>> len(entry.fits_header_entries)  # doctest: +REMOTE_DATA
    111

    """
    headers = fits.get_header(file)

    # This just checks for blank default headers
    # due to compression.
    for header in headers:
        if header == DEFAULT_HEADER:
            headers.remove(header)

    if isinstance(file, str):
        filename = file
    else:
        filename = getattr(file, 'name', None)
    for header in headers:
        entry = DatabaseEntry(path=filename)
        for key, value in header.items():
            # Yes, it is possible to have an empty key in a FITS file.
            # Example: sunpy.data.sample.EIT_195_IMAGE
            # Don't ask me why this could be a good idea.
            if key == '':
                value = str(value)
            elif key == 'KEYCOMMENTS':
                for k, v in value.items():
                    entry.fits_key_comments.append(FitsKeyComment(k, v))
                continue
            entry.fits_header_entries.append(FitsHeaderEntry(key, value))
        waveunit = fits.extract_waveunit(header)
        entry.hdu_index = headers.index(header)
        if waveunit is None:
            waveunit = default_waveunit
        unit = None
        if waveunit is not None:
            try:
                unit = Unit(waveunit)
            except ValueError:
                raise WaveunitNotConvertibleError(waveunit)
        for header_entry in entry.fits_header_entries:
            key, value = header_entry.key, header_entry.value
            if key == 'INSTRUME':
                entry.instrument = value
            elif key == 'WAVELNTH':
#.........这里部分代码省略.........