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sigpyproc.io module

sigpyproc.io module

sigpyproc.io.sigproc

sigpyproc.io.sigproc.edit_header(filename, key, value)

Edit a sigproc style header directly in place for the given file.

Parameters

  • filename (str) – name of the sigproc file to modify header.

  • key (str) – name of parameter to change (must be a valid sigproc key)

  • value (int or float or str) – new value to enter into header

Raises

ValueError – if the new header to be written to file is longer or shorter than the header that was previously in the file.

Notes

It is up to the user to be responsible with this function, as it will directly change the file on which it is being operated.

sigpyproc.io.sigproc.parse_header_multi(filenames, check_contiguity=True)

Parse the metadata from Sigproc-style file/sequential files.

Parameters

filenames (str or list of str) – sigproc filterbank files containing the header

Returns

observational metadata

Return type

dict

sigpyproc.io.sigproc.parse_header(filename)

Parse the metadata from a single Sigproc-style file.

Parameters

filename (str) – sigproc filterbank file containing the header

Returns

observational metadata

Return type

dict

Raises

IOError – If file header is not in sigproc format

sigpyproc.io.sigproc.match_header(header1, header2)

Match header keywords between two parsed sigproc headers.

Parameters

  • header1 (dict) – parsed header from file 1.

  • header2 (dict) – parsed header from file 2.

Raises

ValueError – if key values do not match.

sigpyproc.io.sigproc.ensure_contiguity(header)

Check if list of sigproc files are contiguous/sequential.

Parameters

header (dict) – parsed header of sigproc files

Raises

ValueError – if files are not contiguous

sigpyproc.io.sigproc.encode_header(header)

Get sigproc format header in binary format.

Returns

header in binary format

Return type

bytes

sigpyproc.io.sigproc.encode_key(key, value=None, value_type='str')

Encode given header key to a bytes string.

Parameters

  • key (str) – header key

  • value (int or float or str, optional) – value of the header key, by default None

  • value_type (str, optional) – type of the header key, by default “str”

Returns

bytes encoded string

Return type

bytes

sigpyproc.io.sigproc.parse_radec(src_raj, src_dej)

Parse Sigproc format RADEC float as Astropy SkyCoord.

Parameters

  • src_raj (float) – Sigproc style HHMMSS.SSSS right ascension

  • src_dej (float) – Sigproc style DDMMSS.SSSS declination

Returns

Astropy coordinate class

Return type

SkyCoord

sigpyproc.io.bits

sigpyproc.io.bits.unpack(array, nbits)

Unpack 1, 2 and 4 bit array. Only unpacks in big endian bit ordering.

Parameters

  • array (numpy.ndarray) – Array to unpack.

  • nbits (int) – Number of bits to unpack.

Returns

Unpacked array.

Return type

numpy.ndarray

Raises

ValueError – if nbits is not 1, 2, or 4

sigpyproc.io.bits.pack(array, nbits)

Pack 1, 2 and 4 bit array. Only packs in big endian bit ordering.

Parameters

  • array (numpy.ndarray) – Array to pack.

  • nbits (int) – Number of bits to pack.

Returns

Packed array.

Return type

numpy.ndarray

Raises

ValueError – if nbits is not 1, 2, or 4

class sigpyproc.io.bits.BitsInfo(nbits, digi_sigma=NOTHING)

Bases: object

Class to handle bits info.

Raises

ValueError – if input nbits not in [1, 2, 4, 8, 16, 32]

nbits
digi_sigma
default_sigma = {1: 0.5, 2: 1.5, 4: 6, 8: 6, 16: 6, 32: 6}
property dtype

Type of the data (np.dtype, read-only).

property itemsize

Element size of this data-type object (int, read-only).

property unpack

Whether to unpack bits (bool, read-only).

property bitfact

Bit factor to unpack/pack bits (int, read-only).

property digi_min

Minimum value used to quantize data (int, read-only).

property digi_max

Maximum value used to quantize data (int, read-only).

property digi_mean

Mean used to quantize data (float, read-only).

property digi_scale

Scale used to quantize data (float, read-only).

to_dict()

Get a dict of all property attributes.

Returns

property attributes

Return type

dict

sigpyproc.io.fileio

class sigpyproc.io.fileio.FileReader(files, hdrlens, datalens, mode='r', nbits=8)

Bases: sigpyproc.io.fileio._FileBase

A file reader class that can read from multiple files.

Files should have format similar to sigproc.

Parameters

  • files (list[str]) – list of files to be read from

  • hdrlens (list[int]) – list of header lengths for each file

  • datalens (list[int]) – list of data lengths for each file

  • mode (str, optional) – file opening mode, by default “r”

  • nbits (int, optional) – number of bits per sample in the files, by default 8

property cur_data_pos

Current position in the data stream.

Type

int

cread(nunits)

Read nunits (nbytes) of data from the file.

Parameters

nunits (int) – number of units (nbytes) to be read from the file

Returns

an 1-D array containing the read data

Return type

ndarray

Raises

IOError – if file is closed.

seek(offset, whence=0)

Change the multifile stream position to the given data offset.

offset is always interpreted for a headerless file and is relative to start of the first file.

Parameters

  • offset (int) – Absolute position to seek in the data stream

  • whence (int) – 0 (SEEK_SET) 1 (SEEK_CUR)

Raises

ValueError – if whence is not 0 or 1.

class sigpyproc.io.fileio.FileWriter(file, tsamp, nchans, mode='w', nbits=8, quantize=False, interval_seconds=10, constant_offset_scale=False, **digi_kwargs)

Bases: sigpyproc.io.fileio._FileBase

A file writer class that can write to a sigproc format file.

Parameters

  • file (str) – file to be written to

  • mode (str, optional) – file writing mode, by default “w”

  • nbits (int, optional) – number of bits per sample in the file, by default 8

  • quantize (bool, optional) – whether to quantize the data, by default False

  • tsamp (float, optional) – sampling time, by default None

  • nchans (int, optional) – number of channels, by default None

  • interval_seconds (float, optional) – sample interval used for quantization in seconds, by default 10

  • constant_offset_scale (bool, optional) – whether to use constant offset and scale, by default False

  • **digi_kwargs (dict) – keyword arguments for the digitizer: digi_mean, digi_scale, digi_min, digi_max

Raises

ValueError – if quantize is True and outut nbits is 32.

cwrite(ar)

Write an array to file.

Parameters

ar (ndarray) – a 1-D numpy array

Notes

Regardless of the dtype of the array argument, the data will be packed with a bitsize determined by the nbits attribute of the File instance. To change this attribute, use the _setNbits methods. It is the responsibility of the user to ensure that values in the array do not go beyond the maximum and minimum values allowed by the nbits attribute.

write(bo)

Write the given bytes-like object, bo to the file stream.

Wrapper for io.RawIOBase.write().

Parameters

bo (bytes) – bytes-like object

close()

Close the currently open file object.

class sigpyproc.io.fileio.Transform(tsamp, nchans, digi_mean, digi_scale, digi_min, digi_max, interval_seconds=10, constant_offset_scale=False)

Bases: object

A class to transform data to the quantized format.

Parameters

  • tsamp (float) – sampling time, by default None

  • nchans (int) – number of channels, by default None

  • digi_mean (float) – mean of the quantized data

  • digi_scale (float) – scale of the quantized data

  • digi_min (float) – minimum value of the quantized data

  • digi_max (float) – maximum value of the quantized data

  • interval_seconds (float, optional) – sample interval used for quantization in seconds, by default 10

  • constant_offset_scale (bool, optional) – whether to use constant offset and scale, by default False

property interval_samples
rescale(data)
quantize(data)

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