SetAttribute¶
- class baseband.tasks.SetAttribute(ih, *, start_time=None, sample_rate=None, **kwargs)[source] [edit on github]¶
Bases:
TaskBase
Wrapper for streams that allows one to set or change attributes.
Can be used to add
frequency
,sideband
andpolarization
attributes, which most baseband readers do not provide, checking that the values broadcast properly to the sample shape.Can also be used to apply a clock correction by changing
start_time
.The
sample_rate
can also be set, but no check is done to ensure it remains consistent with thefrequency
.One can also change the
shape
,samples_per_frames
, ordtype
but that will be slightly slower, as the class can then not read directly from the underlying stream.By default, all parameters are taken from the underlying stream.
- Parameters:
- ihstream handle
Handle of a stream reader or another task.
- start_time
Time
, optional Start time of the stream.
- sample_rate
Quantity
, optional With units of a rate.
- **kwargs
Other parameters and metadata. See
TaskBase
.- — Possible metadata(see
BaseTaskBase
) - frequency
Quantity
, optional Frequencies for each channel. Should be broadcastable to the sample shape.
- sidebandarray, optional
Whether frequencies are upper (+1) or lower (-1) sideband. Should be broadcastable to the sample shape.
- polarizationarray or (nested) list of char, optional
Polarization labels. Should broadcast to the sample shape, i.e., the labels are in the correct axis. For instance,
['X', 'Y']
, or[['L'], ['R']]
.
Attributes Summary
Data type of the output.
Number of dimensions of the output.
Number of complete samples per second.
Shape of a complete sample.
Number of samples per frame of data.
Shape of the output.
Number of component samples in the output.
Start time of the output.
Time at the end of the output, just after the last sample.
Time of the sample pointer's current offset in the output.
Methods Summary
close
()Close task.
read
([count, out])Read a number of complete samples.
seek
(offset[, whence])Change the sample pointer position.
simple_read
(*args, **kwargs)Read data from the underlying stream at the current offset.
task
(data)tell
([unit])Current offset in the file.
Attributes Documentation
- closed = False¶
- complex_data¶
- dtype¶
Data type of the output.
- meta¶
- ndim¶
Number of dimensions of the output.
- offset = 0¶
- sample_rate¶
Number of complete samples per second.
- sample_shape¶
Shape of a complete sample.
- samples_per_frame¶
Number of samples per frame of data.
For compatibility with file readers, to help indicate what a nominal chunk of data is.
- shape¶
Shape of the output.
- size¶
Number of component samples in the output.
- stop_time¶
Time at the end of the output, just after the last sample.
See also
start_time
andtime
.
- time¶
Time of the sample pointer’s current offset in the output.
See also
start_time
andstop_time
.
Methods Documentation
- close() [edit on github]¶
Close task.
Note that this does not explicitly close the underlying source; instead, it just deletes the reference to it.
- read(count=None, out=None) [edit on github]¶
Read a number of complete samples.
- Parameters:
- countint or None, optional
Number of complete samples to read. If
None
(default) or negative, the number of samples left. Ignored ifout
is given.- outNone or array, optional
Array to store the samples in. If given,
count
will be inferred from the first dimension; the remaining dimensions should equalsample_shape
.
- Returns:
- out
ndarray
of float or complex The first dimension is sample-time, and the remaining ones are as given by
sample_shape
.
- out
- seek(offset, whence=0) [edit on github]¶
Change the sample pointer 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. For the latter two, the pointer will be moved to the nearest integer sample.
- 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,
- simple_read(*args, **kwargs)[source] [edit on github]¶
Read data from the underlying stream at the current offset.
- task(data)[source] [edit on github]¶
- tell(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: