Exemple #1
0
    def __init__(self, data=None, header=None, do_not_scale_image_data=False,
                 uint=False, scale_back=False, **kwargs):
        from pyfits.hdu.groups import GroupsHDU

        super(_ImageBaseHDU, self).__init__(data=data, header=header)

        if header is not None:
            if not isinstance(header, Header):
                # TODO: Instead maybe try initializing a new Header object from
                # whatever is passed in as the header--there are various types
                # of objects that could work for this...
                raise ValueError('header must be a Header object')

        if data is DELAYED:
            # Presumably if data is DELAYED then this HDU is coming from an
            # open file, and was not created in memory
            if header is None:
                # this should never happen
                raise ValueError('No header to setup HDU.')

            # if the file is read the first time, no need to copy, and keep it
            # unchanged
            else:
                self._header = header
        else:
            # TODO: Some of this card manipulation should go into the
            # PrimaryHDU and GroupsHDU subclasses
            # construct a list of cards of minimal header
            if isinstance(self, ExtensionHDU):
                c0 = ('XTENSION', 'IMAGE',
                      self.standard_keyword_comments['XTENSION'])
            else:
                c0 = ('SIMPLE', True, self.standard_keyword_comments['SIMPLE'])
            cards = [
                c0,
                ('BITPIX',    8, self.standard_keyword_comments['BITPIX']),
                ('NAXIS',     0, self.standard_keyword_comments['NAXIS'])]

            if isinstance(self, GroupsHDU):
                cards.append(('GROUPS', True,
                             self.standard_keyword_comments['GROUPS']))

            if isinstance(self, (ExtensionHDU, GroupsHDU)):
                cards.append(('PCOUNT',    0,
                              self.standard_keyword_comments['PCOUNT']))
                cards.append(('GCOUNT',    1,
                              self.standard_keyword_comments['GCOUNT']))

            if header is not None:
                orig = header.copy()
                header = Header(cards)
                header.extend(orig, strip=True, update=True, end=True)
            else:
                header = Header(cards)

            self._header = header

        self._do_not_scale_image_data = do_not_scale_image_data
        self._uint = uint
        self._scale_back = scale_back

        if do_not_scale_image_data:
            self._bzero = 0
            self._bscale = 1
        else:
            self._bzero = self._header.get('BZERO', 0)
            self._bscale = self._header.get('BSCALE', 1)

        # Save off other important values from the header needed to interpret
        # the image data
        self._axes = [self._header.get('NAXIS' + str(axis + 1), 0)
                      for axis in xrange(self._header.get('NAXIS', 0))]
        self._bitpix = self._header.get('BITPIX', 8)
        self._gcount = self._header.get('GCOUNT', 1)
        self._pcount = self._header.get('PCOUNT', 0)
        self._blank = self._header.get('BLANK')

        self._orig_bitpix = self._bitpix
        self._orig_bzero = self._bzero
        self._orig_bscale = self._bscale

        # Set the name attribute if it was provided (if this is an ImageHDU
        # this will result in setting the EXTNAME keyword of the header as
        # well)
        if 'name' in kwargs and kwargs['name']:
            self.name = kwargs['name']

        # Set to True if the data or header is replaced, indicating that
        # update_header should be called
        self._modified = False

        if data is DELAYED:
            return
        else:
            self.data = data
            self.update_header()
Exemple #2
0
    def load(cls, datafile, cdfile=None, hfile=None, replace=False,
             header=None):
        """
        Create a table from the input ASCII files.  The input is from up to
        three separate files, one containing column definitions, one containing
        header parameters, and one containing column data.

        The column definition and header parameters files are not required.
        When absent the column definitions and/or header parameters are taken
        from the header object given in the header argument; otherwise sensible
        defaults are inferred (though this mode is not recommended).

        Parameters
        ----------
        datafile : file path, file object or file-like object
            Input data file containing the table data in ASCII format.

        cdfile : file path, file object, file-like object, optional
            Input column definition file containing the names,
            formats, display formats, physical units, multidimensional
            array dimensions, undefined values, scale factors, and
            offsets associated with the columns in the table.  If
            `None`, the column definitions are taken from the current
            values in this object.

        hfile : file path, file object, file-like object, optional
            Input parameter definition file containing the header
            parameter definitions to be associated with the table.  If
            `None`, the header parameter definitions are taken from
            the current values in this objects header.

        replace : bool
            When `True`, indicates that the entire header should be
            replaced with the contents of the ASCII file instead of
            just updating the current header.

        header : Header object
            When the cdfile and hfile are missing, use this Header object in
            the creation of the new table and HDU.  Otherwise this Header
            supercedes the keywords from hfile, which is only used to update
            values not present in this Header, unless replace=True in which
            this Header's values are completely replaced with the values from
            hfile.

        Notes
        -----
        The primary use for the `load` method is to allow the input of ASCII
        data that was edited in a standard text editor of the table data and
        parameters.  The `dump` method can be used to create the initial ASCII
        files.
        """

        # Process the parameter file
        if header is None:
            header = Header()

        if hfile:
            if replace:
                header = Header.fromtextfile(hfile)
            else:
                header.extend(Header.fromtextfile(hfile), update=True,
                              update_first=True)

        coldefs = None
        # Process the column definitions file
        if cdfile:
            coldefs = cls._load_coldefs(cdfile)

        # Process the data file
        data = cls._load_data(datafile, coldefs)
        if coldefs is None:
            coldefs = ColDefs(data)

        # Create a new HDU using the supplied header and data
        hdu = cls(data=data, header=header)
        hdu.columns = coldefs
        return hdu