netcdf-c/nczarr_test/ref_ut_map_writemeta2.cdl
Dennis Heimbigner 2afbdbd18f Add support for the XArray Zarr _ARRAY_DIMENSIONS attribute
The XArray implementation that uses Zarr for storage
provides a mechanism to simulate named dimensions.
It does this by adding a per-variable attribute called
_ARRAY_DIMENSIONS. This attribute contains a list of names
to be matched against the shape values of the variable.
In effect a named dimension is created with the name
_ARRAY_DIMENSIONS(i) and length shape(i) for all i
in range 0..rank(variable).
Both read and write support is provided.

This XArray support is only invoked if the mode value
of "xarray" is defined. So for example, as in this URL.
````
https://s3.us-west-1.amazonaws.com/bucket/dataset#mode=nczarr,xarray,s3
````
Note that the "xarray" mode flag also implies mode flag "zarr", so the above
is equivalent to this URL.
````
https://s3.us-west-1.amazonaws.com/bucket/dataset#mode=nczarr,zarr,xarray,s3
````

The primary change to implement this was to unify the handling
of dimension references in libnczarr/zsync.

A test for this and other pure-zarr features was added as
nczarr_test/run_purezarr.sh

Other changes:
* Make sure distcheck leaves no files around.
* Change the special attribute flag DIMSCALEFLAG to HIDDENATTRFLAG
  to support the xarray attribute.
* Annotate the zmap implementations with feature flags such as
  WRITEONCE (for zip files).
2021-02-24 13:46:11 -07:00

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[0] /.nczarr : (0) ||
[2] /meta1/.zarray : (50) |{
"foo": 42,
"bar": "apples",
"baz": [1, 2, 3, 4]}|
[4] /meta2/.nczarray : (64) |{
"foo": 42,
"bar": "apples",
"baz": [1, 2, 3, 4],
"extra": 137}|