DADAFileReader¶
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class
baseband.dada.base.
DADAFileReader
(fh_raw)[source] [edit on github]¶ Bases:
baseband.vlbi_base.base.VLBIFileReaderBase
Simple reader for DADA files.
Wraps a binary filehandle, providing methods to help interpret the data, such as
read_frame
andget_frame_rate
. By default, frame payloads are mapped rather than fully read into physical memory.Parameters: fh_raw : filehandle
Filehandle of the raw binary data file.
Attributes Summary
info
Standardized information on file readers. Methods Summary
close
()get_frame_rate
()Determine the number of frames per second. read_frame
([memmap, verify])Read the frame header and read or map the corresponding payload. read_header
()Read a single header from the file. Attributes Documentation
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info
¶ Standardized information on file readers.
The
info
descriptor has a number of standard attributes, which are determined from arguments passed in opening the file, from the first header (info.header0
) and from possibly scanning the file to determine the duration of frames.Examples
The most common use is simply to print information:
>>> from baseband.data import SAMPLE_MARK5B >>> from baseband import mark5b >>> fh = mark5b.open(SAMPLE_MARK5B, 'rb') >>> fh.info File information: format = mark5b frame_rate = 6400.0 Hz bps = 2 complex_data = False missing: nchan: needed to determine sample shape and rate. kday, ref_time: needed to infer full times. >>> fh.close() >>> fh = mark5b.open(SAMPLE_MARK5B, 'rb', kday=56000, nchan=8) >>> fh.info File information: format = mark5b frame_rate = 6400.0 Hz sample_rate = 32.0 MHz samples_per_frame = 5000 sample_shape = (8,) bps = 2 complex_data = False start_time = 2014-06-13T05:30:01.000000000 >>> fh.close()
Attributes
format (str or None
) File format, orNone
if the underlying file cannot be parsed.frame_rate ( Quantity
) Number of data frames per unit of time.sample_rate ( Quantity
) Complete samples per unit of time.samples_per_frame (int) Number of complete samples in each frame. sample_shape (tuple) Dimensions of each complete sample (e.g., (nchan,)
).bps (int) Number of bits used to encode each elementary sample. complex_data (bool) Whether the data are complex. start_time ( Time
) Time of the first complete sample.missing (dict) Entries are keyed by names of arguments that should be passed to the file reader to obtain full information. The associated entries explain why these arguments are needed.
Methods Documentation
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close
() [edit on github]¶
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get_frame_rate
()[source] [edit on github]¶ Determine the number of frames per second.
The routine uses the sample rate and number of samples per frame from the first header in the file.
Returns: frame_rate :
Quantity
Frames per second.
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read_frame
(memmap=True, verify=True)[source] [edit on github]¶ Read the frame header and read or map the corresponding payload.
Parameters: memmap : bool, optional
verify : bool, optional
Whether to do basic checks of frame integrity. Default:
True
.Returns: frame :
DADAFrame
With
.header
and.payload
properties. The.data
property returns all data encoded in the frame. Since this may be too large to fit in memory, it may be better to access the parts of interest by slicing the frame.
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read_header
()[source] [edit on github]¶ Read a single header from the file.
Returns: header : DADAHeader
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