[gdal-dev] How to wrap a zarr in a zip and read it with vsizip?

[Michael Sumner]

Just clueing into why you might be working with this, have you seen this
critique?  (was a bit shocked to see that this is apparently going forward
for Sentinel 2, let alone that it was even considered!)

https://github.com/csaybar/ESA-zar-zip-decision

Also glad to see a working example outlined that I can follow, Thanks!

Cheers, Mike



On Tue, Feb 25, 2025 at 7:10 AM Kurt Schwehr via gdal-dev <
gdal-dev at lists.osgeo.org> wrote:

> Thanks Laurentiu and Scott!
>
> I can't believe 1) I left off -r and 2) I didn't think to look at what's
> in the zip. Doh!
>
> And thanks for reminding me about sozip. I was one of the reviewers of the
> initial spec and still don't have it front-of-mind.
>
> unzip -l nczarr_v2.zarr.zip
> Archive:  nczarr_v2.zarr.zip
>   Length      Date    Time    Name
> ---------  ---------- -----   ----
>         0  2024-12-23 02:00   nczarr_v2.zarr/
> ---------                     -------
>         0                     1 file
>
> Now happily able to see the contents:
>
> gdalinfo /vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr
> Driver: Zarr/Zarr
> Files: /vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr
> Size is 512, 512
> Subdatasets:
>
> SUBDATASET_1_NAME=ZARR:"/vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr":/MyGroup/lon
>   SUBDATASET_1_DESC=Array /MyGroup/lon
>
> SUBDATASET_2_NAME=ZARR:"/vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr":/MyGroup/lat
>   SUBDATASET_2_DESC=Array /MyGroup/lat
>
> SUBDATASET_3_NAME=ZARR:"/vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr":/MyGroup/dset1
>   SUBDATASET_3_DESC=Array /MyGroup/dset1
>
> SUBDATASET_4_NAME=ZARR:"/vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr":/MyGroup/Group_A/dset2
>   SUBDATASET_4_DESC=Array /MyGroup/Group_A/dset2
>
> SUBDATASET_5_NAME=ZARR:"/vsizip/nczarr_v2.zarr.zip/nczarr_v2.zarr":/MyGroup/Group_A/dset3
>   SUBDATASET_5_DESC=Array /MyGroup/Group_A/dset3
> [SNIP]
>
> -Kurt
>
> On Mon, Feb 24, 2025 at 11:21 AM Laurențiu Nicola via gdal-dev <
> gdal-dev at lists.osgeo.org> wrote:
>
>> I suspect it won't make a lot of difference. SOZIP is designed to allow
>> seeking within a compressed file, but Zarr is tile- (block) based, where
>> each of those is stored in a different file. So you end up uncompressing a
>> whole file anyway.
>>
>> Laurentiu
>>
>> On Mon, Feb 24, 2025, at 21:17, Scott via gdal-dev wrote:
>> > There's GDAL's sozip (Search Optimized Zip) utility as well. I have no
>> > idea if it works with .zarr. I'm sure someone will correct me! ;)
>> >
>> > cd nczarr_v2.zarr
>> > sozip ../nczarr_v2.zarr.zip .
>> > sozip -l /vsizip/../nczarr_v2.zarr.zip
>> >
>> > On 2/24/25 10:09, Kurt Schwehr via gdal-dev wrote:
>> >> Hi all,
>> >>
>> >> I seem to be having trouble exactly how to correctly make a zip of a
>> >> zarr and how to correctly specify the vsizip url.
>> >>
>> >> e.g from autotest/gdrivers/data/zarr
>> >>
>> >> gdalinfo nczarr_v2.zarr # Works
>> >> tar cf nczarr_v2.zarr.zip nczarr_v2.zarr
>> >>
>> >> Then what? I've tried lots of variations and not had any success.
>> >>
>> >> Thanks!
>> >> -Kurt
>> >>
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-- 
Michael Sumner
Research Software Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner at gmail.com
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