10th April, 2019

Time: 20:00 GMT (16:00 EDT).

Joining instructions see above.

Attendees: RyanW (1x) / MartinD, RyanA, JoshM, FabianG (2x) / JohnK (1x)

Please feel free to propose an item for the agenda below. If you do, please include your name so we know who proposed the item.

Standing items

• Introductions: new joinees should feel welcome to introduce themselves and their interest in zarr/n5.

Topics

• Timezones

  • Josh: Propose to move 20 GMT to 20 BST (i.e. whatever 8pm is in

    the UK and/or whatever google calendar says)

  • See agenda for the 24th.

• John: summary of past few missed meetings

  • E.g. Martin’s work.

  • Back to specs…

• Specs

  • Handling sparse arrays (what is TileDB do here)

  • https://docs.tiledb.io/en/stable/tutorials/format-description.html?highlight=specification

  • RyanA: Need to focus on a spec that is well scoped (not to

    general) for our needs

  • JohnK: start with types?

  • Josh: cF.

    https://github.com/imglib/imglib2/tree/master/src/main/java/net/imglib2/type has a complex type

  • JohnK: mix in zarr is problematic, also can’t define default

    complex

    • Josh: memory layout probably needs to be written in json, could also use for fill values

    • JohnK: see https://github.com/zarr-developers/zarr/issues/354

    • Josh: json-ld?? { “@id”: …., }


    • https://stdlib.io/develop/docs/api/@stdlib/complex/float64/


      • {
 “type”: “Complex128”,
 “re”: 5.0,
 “im”: -3.0
 }


    • 
https://github.com/josdejong/mathjs/issues/27


      • {
 “mathjson”: “complex”,
 “real”: 3,
 “imag”: 4
}


  • John: Even worse are timestamps

    • https://json-tricks.readthedocs.io/en/latest/#preserve-type-vs-use-primitive
    • Fabian: in geo / netcdf world, use “days since” (e.g.) then a float. Ignoring leap seconds. Works despite precision issues.

  • Fabian: good to have whatever implemented in C

    • Balancing usefulness and complexity across multiple languages

  • Structured arrays:

    • Josh: Tuple of chunks rather than chunk of tuples ?
    • John: will ask for one particular use case
    • cF. coordinate selection
      https://github.com/zarr-developers/zarr/blob/master/zarr/core.py#L1455-L1493

• Working on presentation material

  • SciPy early July

  • Josh late July in Basel.