Data Recorder Module

class joulescope.data_recorder.DataReader

Read Joulescope data from a file.

close()

Close the recording file.

data_get(start, stop, increment=None, units=None, out=None)

Get the samples with statistics.

Parameters:

• start – The starting sample id (inclusive).
• stop – The ending sample id (exclusive).
• increment – The number of raw samples.
• units – The units for start and stop. ‘seconds’ or None is in floating point seconds relative to the view. ‘samples’ is in stream buffer sample indices.
• out – The optional output np.ndarray((N, STATS_FIELD_COUNT), dtype=DTYPE) to populate with the result. None (default) will construct and return a new array.

Returns:

The np.ndarray((N, STATS_FIELD_COUNT), dtype=DTYPE) data.

duration

The data file duration, in seconds.

get_reduction(start=None, stop=None, units=None, out=None)

Get the fixed reduction with statistics.

Parameters:

• start – The starting sample identifier (inclusive).
• stop – The ending sample identifier (exclusive).
• units – The units for start and stop. ‘seconds’ or None is in floating point seconds relative to the view. ‘samples’ is in stream buffer sample indices.

Returns:

The The np.ndarray((N, STATS_FIELD_COUNT), dtype=DTYPE) reduction data which normally is memory mapped to the underlying data, but will be copied on rollover.

input_sampling_frequency

The original input sampling frequency.

normalize_time_arguments(start, stop, units=None)

Normalize time arguments to range.

Parameters:

• start – The start time or samples. None gets the first sample, equivalent to self.sample_id_range[0].
• stop – The stop time or samples. None gets the last sample, equivalent to self.sample_id_range[1].
• units – The time units which is one of [‘seconds’, ‘samples’] None (default) id equivalent to ‘samples’.

Returns:

(start_sample, stop_sample).

When units==’samples’, negative values are interpreted in standard Python notation relative to the last sample. None

open(filehandle)

Open a recording file.

Parameters:filehandle – The seekable filehandle or filename string.

output_sampling_frequency

The output sampling frequency.

reduction_frequency

The reduction frequency or 1 if no reduction.

sample_id_range

The sample ID range.

Returns:[start, stop] sample identifiers.

samples_get(start=None, stop=None, units=None, fields=None)

Get exact samples over a range.

Parameters:

• start – The starting time.
• stop – The ending time.
• units – The units for start and stop. ‘seconds’ or None is in floating point seconds relative to the view. ‘samples’ is in stream buffer sample indicies.
• fields – The fields to get.

sampling_frequency

The output sampling frequency.

statistics_get(start=None, stop=None, units=None)

Get the statistics for the collected sample data over a time range.

Parameters:

• start – The starting time relative to the first sample.
• stop – The ending time.
• units – The units for start and stop. ‘seconds’ is in floating point seconds relative to the view. ‘samples’ or None is in stream buffer sample indices.

Returns:

The statistics data structure. See joulescope.stream_buffer.stats_to_api() for details.

voltage_range

The data file voltage range.

class joulescope.data_recorder.DataRecorder(filehandle, calibration=None, user_data=None)

Record Joulescope data to a file.

Parameters:

• filehandle – The file-like object or file name.
• calibration – The calibration bytes in datafile format. None (default) uses the unit gain calibration.
• user_data – Arbitrary JSON-serializable user data that is added to the file.

close()

Finalize and close the recording.

insert(data)

Insert sample data.

Parameters:data – A dict in the StreamBuffer.samples_get() format.

stream_notify(stream_buffer)

Process data from a stream buffer.

Parameters:stream_buffer – The stream_buffer instance which has: * “output_sampling_frequency” member -> float * “has_raw” member -> in [True, False] * “sample_id_range” member => (start, stop) * “voltage_range” member -> in [0, 1] * samples_get(start_sample_id, stop_sample_id, dtype) * data_get(start_sample_id, stop_sample_id, increment, out) * __len__ : maximum number of samples that stream_buffer holds