def create_filterbank_file(outfn, header, spectra=None, nbits=8, \
verbose=False, mode='append'):
"""Write filterbank header and spectra to file.
Input:
outfn: The outfile filterbank file's name.
header: A dictionary of header paramters and values.
spectra: Spectra to write to file. (Default: don't write
any spectra - i.e. write out header only)
nbits: The number of bits per sample of the filterbank file.
This value always overrides the value in the header dictionary.
(Default: 8 - i.e. each sample is an 8-bit integer)
verbose: If True, be verbose (Default: be quiet)
mode: Mode for writing (can be 'append' or 'write')
Output:
fbfile: The resulting FilterbankFile object opened
in read-write mode.
"""
dtype = get_dtype(nbits) # Get dtype. This will check to ensure
# 'nbits' is valid.
header['nbits'] = nbits
outfile = open(outfn, 'wb')
outfile.write(sigproc.addto_hdr("HEADER_START", None))
for paramname in header.keys():
if paramname not in sigproc.header_params:
# Only add recognized parameters
continue
if verbose:
print "Writing header param (%s)" % paramname
value = header[paramname]
outfile.write(sigproc.addto_hdr(paramname, value))
outfile.write(sigproc.addto_hdr("HEADER_END", None))
if spectra is not None:
spectra.flatten().astype(dtype).tofile(outfile)
outfile.close()
return FilterbankFile(outfn, mode=mode)
def write_spectra(self, spectra, ispec):
"""Write spectra to the file if is writable.
Input:
spectra: The spectra to append. The new spectra
must have the correct number of channels (ie
dimension of axis=1.
ispec: The index of the spectrum of where to start writing.
Outputs:
None
"""
if 'r+' not in self.filfile.mode.lower():
raise ValueError("FilterbankFile object for '%s' is not writable." % \
self.filename)
nspec, nchans = spectra.shape
if nchans != self.nchans:
raise ValueError("Cannot write spectra. Incorrect shape. " \
"Number of channels in file: %d; Number of " \
"channels in spectra to write: %d" % \
(self.nchans, nchans))
if ispec > self.nspec:
raise ValueError("Cannot write past end of file! " \
"Present number of spectra: %d; " \
"Requested index of write: %d" % \
(self.nspec, ispec))
data = spectra.flatten()
np.clip(data, self.dtype_min, self.dtype_max, out=data)
# Move to requested position
pos = self.header_size + ispec * self.bytes_per_spectrum
self.filfile.seek(pos, os.SEEK_SET)
self.filfile.write(data.astype(self.dtype))
if nspec + ispec > self.nspec:
self.nspec = nspec + ispec
def append_spectra(self, spectra):
"""Append spectra to the file if is not read-only.
Input:
spectra: The spectra to append. The new spectra
must have the correct number of channels (ie
dimension of axis=1.
Outputs:
None
"""
if self.filfile.mode.lower() in ('r', 'rb'):
raise ValueError("FilterbankFile object for '%s' is read-only." % \
self.filename)
nspec, nchans = spectra.shape
if nchans != self.nchans:
raise ValueError("Cannot append spectra. Incorrect shape. " \
"Number of channels in file: %d; Number of " \
"channels in spectra to append: %d" % \
(self.nchans, nchans))
data = spectra.flatten()
np.clip(data, self.dtype_min, self.dtype_max, out=data)
# Move to end of file
self.filfile.seek(0, os.SEEK_END)
self.filfile.write(data.astype(self.dtype))
self.nspec += nspec