open

baseband.vdif.base.open(name, mode=u'rs', **kwargs)

Open VDIF file(s) for reading or writing.

Opened as a binary file, one gets a wrapped filehandle that adds methods to read/write a frame. Opened as a stream, the handle is wrapped further, with methods such as reading and writing to the file as if it were a stream of samples.

Parameters:

name : str or filehandle, or sequence of str

File name, filehandle, or sequence of file names (see Notes).

mode : {‘rb’, ‘wb’, ‘rs’, or ‘ws’}, optional

Whether to open for reading or writing, and as a regular binary file or as a stream. Default: ‘rs’, for reading a stream.

**kwargs

Additional arguments when opening the file as a stream.

— For reading a stream : (see VDIFStreamReader)

sample_rate : Quantity, optional

Number of complete samples per second, i.e. the rate at which each channel in each thread is sampled. If None (default), will be inferred from the header or by scanning one second of the file.

squeeze : bool, optional

If True (default), remove any dimensions of length unity from decoded data.

subset : indexing object or tuple of objects, optional

Specific components of the complete sample to decode (after possible squeezing). If a single indexing object is passed, it selects threads. If a tuple is passed, the first selects threads and the second selects channels. If the tuple is empty (default), all components are read.

fill_value : float or complex, optional

Value to use for invalid or missing data. Default: 0.

verify : bool, optional

Whether to do basic checks of frame integrity when reading. The first frameset of the stream is always checked. Default: True.

— For writing a stream : (see VDIFStreamWriter)

header0 : VDIFHeader

Header for the first frame, holding time information, etc. Can instead give keyword arguments to construct a header (see **kwargs).

sample_rate : Quantity

Number of complete samples per second, i.e. the rate at which each channel in each thread is sampled. For EDV 1 and 3, can alternatively set sample_rate within the header.

nthread : int, optional

Number of threads (e.g., 2 for 2 polarisations). Default: 1.

squeeze : bool, optional

If True (default), writer accepts squeezed arrays as input, and adds any dimensions of length unity.

file_size : int or None, optional

When writing to a sequence of files, the maximum size of one file in bytes. If None (default), the file size is unlimited, and only the first file will be written to.

**kwargs

If the header is not given, an attempt will be made to construct one with any further keyword arguments. See VDIFStreamWriter.

Notes

One can also pass to name a list, tuple, or subclass of FileNameSequencer. For writing to multiple files, the file_size keyword must be passed or only the first file will be written to. One may also pass in a sequentialfile object (opened in ‘rb’ mode for reading or ‘w+b’ for writing), though for typical use cases it is practically identical to passing in a list or template.