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40 changes: 40 additions & 0 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,48 @@ This textbook gives scientists:
- a guide to designing parallel processing algorithms to work efficiently with chunked datasets
- a guide to exporting chunked datasets to other 'tradditional' datasets

## Benchmarking for Zarr

We created a [set of benchmarks](https://github.com/HEFTIEProject/zarr-benchmarks) for reading / writing data to Zarr with a range of different configurations. These benchmarks provide guidance on how selection of different configurations affect data size and read/write performance.
The different parameters were:
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Link to the final report?
e.g. 'The final benchmarking results are summarised into a short report to help researchers choose the best options for their image datasets'


- Type of image
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Here you're mixing the different parameters (e.g. type of image = heart / dense /sparse) with benchmarking results (e.g. compressor = blosc-zstd provides the best compression ratio). Maybe just list the different parameters options here, and link to the final report for results? Not sure what @dstansby 's preference is.

- Heart: HiP-CT scan of a heart from the Human Organ Atlas
- Dense: segmented neurons from electron microscopy
- Sparse: A few select segmented neurons from electron microscopy
- Software libraries
- Tensorstore (fastest for both reading and writing data)
- zarr-python version 3
- zarr-python version 2 (slowest for both reading and writing data)
- Compressor
- blosc-zstd provides the best compression ratio, for image and segmentation data. (options were blosc-blosclz, blosc-lz4, blosc-lz4hc, blosc-zlib, blosc-zstd as well as gzip and zstd)
- Compression level
- Setting compression levels beyond ~3 results in slightly better data compression but much longer write times. Compression level does not affect read time.
- Shuffle
- Setting the shuffle option increases data compression with no adverse effect on read/write times (shuffle, bitshuffle and noshuffle were the 3 options)
- Zarr format version
- There was no noticeable difference between Zarr format 2 and Zarr format 3 data
- Chunk size
- Setting a low chunk size (below around 90) has an adverse effect on read and write times.

## Tools for working with chunked datasets

Contributions have been made to the zarr-python repository:
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Do we need a brief description of what each of these contributions does + why it was useful? Again, not sure how much detail we need to go into here


- [Add CLI for converting v2 metadata to v3](https://github.com/zarr-developers/zarr-python/pull/3257)
- [Added ArrayNotFoundError](https://github.com/zarr-developers/zarr-python/pull/3367)
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Not sure if we want to include them, but I did do a couple of other minor PRs:

- [Better document acceptable values for StoreLike](https://github.com/zarr-developers/zarr-python/pull/3480)

PRs have been opened in the zarr-python repository:

- [Prevent creation of arrays/groups under a parent array](https://github.com/zarr-developers/zarr-python/pull/3407)
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This PR (prevent creation of arrays/groups../) has been merged now - so can move up into 'contributions made'

- [Holding space - LRUStoreCache]

PRs have also been opened for:
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Only issues have been opened for dask / skimage - not PRs


- [Document supported file formats for dask_image.imread](https://github.com/dask/dask-image/issues/407)
- [Document supported file formats for skimage.io](https://github.com/scikit-image/scikit-image/issues/7879)

## Improvements to cloud visualisation

## Acknowledgements