def hdulist(self): self._file.seek(self._datLoc) fileobj = BytesIO() # Read the data into a BytesIO--reading directly from the file # won't work (at least for gzipped files) due to problems deep # within the gzip module that make it difficult to read gzip files # embedded in another file fileobj.write(self._file.read(self.size)) fileobj.seek(0) if self._header['COMPRESS']: fileobj = gzip.GzipFile(fileobj=fileobj) return HDUList.fromfile(fileobj, mode='readonly')
def __init__(self, name, header): """ Construct a `StreamingHDU` object given a file name and a header. Parameters ---------- name : file path, file object, or file like object The file to which the header and data will be streamed. If opened, the file object must be opened for append (ab+). header : `Header` instance The header object associated with the data to be written to the file. Notes ----- The file will be opened and the header appended to the end of the file. If the file does not already exist, it will be created, and if the header represents a Primary header, it will be written to the beginning of the file. If the file does not exist and the provided header is not a Primary header, a default Primary HDU will be inserted at the beginning of the file and the provided header will be added as the first extension. If the file does already exist, but the provided header represents a Primary header, the header will be modified to an image extension header and appended to the end of the file. """ if isinstance(name, gzip.GzipFile): raise TypeError('StreamingHDU not supported for GzipFile objects.') self._header = header.copy() # handle a file object instead of a file name filename = fileobj_name(name) or '' # # Check if the file already exists. If it does not, check to see # if we were provided with a Primary Header. If not we will need # to prepend a default PrimaryHDU to the file before writing the # given header. # newfile = False if filename: if not os.path.exists(filename) or os.path.getsize(filename) == 0: newfile = True elif (hasattr(name, 'len') and name.len == 0): newfile = True if newfile: if 'SIMPLE' not in self._header: hdulist = HDUList([PrimaryHDU()]) hdulist.writeto(name, 'exception') else: # # This will not be the first extension in the file so we # must change the Primary header provided into an image # extension header. # if 'SIMPLE' in self._header: self._header.set('XTENSION', 'IMAGE', 'Image extension', after='SIMPLE') del self._header['SIMPLE'] if 'PCOUNT' not in self._header: dim = self._header['NAXIS'] if dim == 0: dim = '' else: dim = str(dim) self._header.set('PCOUNT', 0, 'number of parameters', after='NAXIS' + dim) if 'GCOUNT' not in self._header: self._header.set('GCOUNT', 1, 'number of groups', after='PCOUNT') self._ffo = _File(name, 'append') # TODO : Fix this once the HDU writing API is cleaned up tmp_hdu = _BaseHDU() # Passing self._header as an argument to _BaseHDU() will cause its # values to be modified in undesired ways...need to have a better way # of doing this tmp_hdu._header = self._header self._header_offset = tmp_hdu._writeheader(self._ffo)[0] self._data_offset = self._ffo.tell() self._size = self.size if self._size != 0: self.writecomplete = False else: self.writecomplete = True