What is the definition of the logical unit of a Segment, or why is there no Segment.time_slice()?

[Georg Raiser]

Taken from the docs:

A Segment is a heterogeneous container for discrete or continuous data sharing a common clock (time basis) but not necessary the same sampling rate, start or end time.

What is meant by this, exactly? What is a "common clock"? If the individual data children can have arbitrary t_start and t_stop as well as sampling rates, what "shared time basis" is still uniting them into a logical group?

As it looks like in the neo core diagram, all elements of a segment share a common t_start and t_stop. If different measurements have different sampling rates, then of course having a shared t_start and t_stop is quite impossible, but if the time basis is made flexible, what logical grouping basis is left?

I ask this question, because I was looking for a .time_slice() method of a segment. That would be an extremely useful thing, if a segment is meant to be used as a temporal logical unit.

Thanks, Georg

[Samuel Garcia]

Hi,
basically this mean that object inside a Segment have a compatible timeline.
So you can align spikes, events and signals for analyses inside a Segment (PSTH, phase lock, ...)

This is not always the case for objects inside a Block, because Segment inside a Block can "reset" the clock for each Segment in some recording device that do not have absolute time.

Even it is not intuitive, a Segment do not have borders (t_start/t_stop).
Only objects (AnalogSignal, Events, Spiketrain) inside the Segment have borders (t_start/t_stop).
This is for covering the case when 2 devices (aligned in time) have recorded the same thing but with different start/stop.
So object have time_slice but not Segment do not have.

We could add a convenient Segment.time_slice and the meaning would be "slice all object inside this Segment".
Note that even in that case this will ensure that all object will have the same t_start for complicated cases.


Could you open an Issue ? (I guess there is already one about this).


Best


Samuel

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