fNIRS / snirf

SNIRF Format Specification
http://fnirs.org/resources/software/snirf/
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Remove incomplete local channel indexing #151

Closed samuelpowell closed 3 months ago

samuelpowell commented 4 months ago

The current implementation of local channel indexing is incomplete, because there is no defined mapping from local indices to global indices.

We further note that all practical purposes (e.g. analysis) a global index is required.

It is recognised that local indices do provide additional information. For example, there may be differing noise characteristics in the data which are dependent upon the local indices. However, capturing this information by means of indexing is vendor specific, and exploitation requires an intimate knowledge of the system.

If it is decided that such information should be retained, this should be done in a vendor agnostic and explicit manner. For example, in the case of noise characteristics, a per-channel noise distribution could be specified. But more generally, further design is required to understand how to most flexibilty translate the qualities of the acquistion system to the analysis phase, consider e.g., #141.

Thus, on balance, it has been decided to remove the current local indexing implementation.

We believe that the lack of specificaion of a mapping from local to global indexing means that it is not possible to have produced a compliant SNIRF file using local indexing, and hence this change is non-breaking.

Fix #106.

dboas commented 3 months ago

@rob-luke and @sstucker can you two review this pull request ASAP!

Your review has been requested and other urgent things are waiting for this pull request to be approved. Thanks