GSBStreamReader¶
-
class
baseband.gsb.base.
GSBStreamReader
(fh_ts, fh_raw, sample_rate=None, samples_per_frame=None, payload_nbytes=None, nchan=None, bps=None, complex_data=None, squeeze=True, subset=(), verify=True)[source] [edit on github]¶ Bases:
baseband.gsb.base.GSBStreamBase
,baseband.vlbi_base.base.VLBIStreamReaderBase
GSB format reader.
Allows access to GSB files as a continuous series of samples. Requires both a timestamp and one or more corresponding raw data files.
- Parameters
- fh_ts
GSBTimeStampIO
Header filehandle.
- fh_rawfilehandle, or nested tuple of filehandles
Raw binary data filehandle(s). A single file is needed for rawdump, and a tuple for phased. For a nested tuple, the outer tuple determines the number of polarizations, and the inner tuple(s) the number of streams per polarization. E.g.,
((polL1, polL2), (polR1, polR2))
for two streams per polarization. A single tuple is interpreted as streams of a single polarization.- sample_rate
Quantity
, optional Number of complete samples per second, i.e. the rate at which each channel of each polarization is sampled. If
None
, will be inferred assuming the frame rate is exactly 0.25165824 s.- samples_per_frameint, optional
Number of complete samples per frame. Can give
payload_nbytes
instead.- payload_nbytesint, optional
Number of bytes per payload, divided by the number of raw files. If both
samples_per_frame
andpayload_nbytes
areNone
,payload_nbytes
is set to2**22
(4 MB) for rawdump, and2**23
(8 MB) divided by the number of streams per polarization for phased.- nchanint, optional
Number of channels. Default: 1 for rawdump, 512 for phased.
- bpsint, optional
Bits per elementary sample, i.e. per real or imaginary component for complex data. Default: 4 for rawdump, 8 for phased.
- complex_databool, optional
Whether data are complex. Default:
False
for rawdump,True
for phased.- squeezebool, optional
If
True
(default), remove any dimensions of length unity from decoded data.- subsetindexing object or tuple of objects, optional
Specific components of the complete sample to decode (after possibly squeezing). If a single indexing object is passed, it selects (available) polarizations. If a tuple is passed, the first selects polarizations and the second selects channels. If the tuple is empty (default), all components are read.
- verifybool, optional
Whether to do basic checks of frame integrity when reading. The first frame of the stream is always checked. Default:
True
.
- fh_ts
Attributes Summary
Bits per elementary sample.
Whether the data are complex.
Value to use for invalid or missing data.
First header of the file.
info
()Number of dimensions of the (squeezed/subset) stream data.
Number of complete samples per second.
Shape of a complete sample (possibly subset or squeezed).
Number of complete samples per frame.
Shape of the (squeezed/subset) stream data.
Total number of component samples in the (squeezed/subset) stream data.
Whether data arrays have dimensions with length unity removed.
Start time of the file.
Time at the end of the file, just after the last sample.
Specific components of the complete sample to decode.
Time of the sample pointer’s current offset in file.
Whether to do consistency checks on frames being read.
Methods Summary
close
(self)read
(self[, count, out])Read a number of complete (or subset) samples.
readable
(self)Whether the file can be read and decoded.
seek
(self, offset[, whence])Change the stream position.
tell
(self[, unit])Current offset in the file.
Attributes Documentation
-
bps
¶ Bits per elementary sample.
-
complex_data
¶ Whether the data are complex.
-
dtype
¶
-
fill_value
¶ Value to use for invalid or missing data. Default: 0.
-
header0
¶ First header of the file.
-
info
¶
-
ndim
¶ Number of dimensions of the (squeezed/subset) stream data.
-
sample_rate
¶ Number of complete samples per second.
-
sample_shape
¶ Shape of a complete sample (possibly subset or squeezed).
-
samples_per_frame
¶ Number of complete samples per frame.
-
shape
¶ Shape of the (squeezed/subset) stream data.
-
size
¶ Total number of component samples in the (squeezed/subset) stream data.
-
squeeze
¶ Whether data arrays have dimensions with length unity removed.
If
True
, data read out has such dimensions removed, and data passed in for writing has them inserted.
-
start_time
¶ Start time of the file.
See also
time
for the time of the sample pointer’s current offset, and (if available)stop_time
for the time at the end of the file.
-
stop_time
¶ Time at the end of the file, just after the last sample.
See also
start_time
for the start time of the file, andtime
for the time of the sample pointer’s current offset.
-
subset
¶ Specific components of the complete sample to decode.
The order of dimensions is the same as for
sample_shape
. Set by the class initializer.
-
time
¶ Time of the sample pointer’s current offset in file.
See also
start_time
for the start time, and (if available)stop_time
for the end time, of the file.
-
verify
¶ Whether to do consistency checks on frames being read.
Methods Documentation
-
close
(self) [edit on github]¶
-
read
(self, count=None, out=None) [edit on github]¶ Read a number of complete (or subset) samples.
The range retrieved can span multiple frames.
- Parameters
- countint or None, optional
Number of complete/subset samples to read. If
None
(default) or negative, the whole file is read. Ignored ifout
is given.- outNone or array, optional
Array to store the data in. If given,
count
will be inferred from the first dimension; the other dimension should equalsample_shape
.
- Returns
- out
ndarray
of float or complex The first dimension is sample-time, and the remainder given by
sample_shape
.
- out
-
readable
(self)[source] [edit on github]¶ Whether the file can be read and decoded.
-
seek
(self, offset, whence=0) [edit on github]¶ Change the stream position.
This works like a normal filehandle seek, but the offset is in samples (or a relative or absolute time).
- Parameters
- offsetint,
Quantity
, orTime
Offset to move to. Can be an (integer) number of samples, an offset in time units, or an absolute time.
- whence{0, 1, 2, ‘start’, ‘current’, or ‘end’}, optional
Like regular seek, the offset is taken to be from the start if
whence=0
(default), from the current position if 1, and from the end if 2. One can alternativey use ‘start’, ‘current’, or ‘end’ for 0, 1, or 2, respectively. Ignored ifoffset
is a time.
- offsetint,
-
tell
(self, unit=None) [edit on github]¶ Current offset in the file.
- Parameters
- unit
Unit
or str, optional Time unit the offset should be returned in. By default, no unit is used, i.e., an integer enumerating samples is returned. For the special string ‘time’, the absolute time is calculated.
- unit
- Returns