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Add scale_offset array->array codec - #87
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Implements the zarr-extensions scale_offset codec: encode applies (in - offset) * scale, decode applies (in / scale) + offset, in the input data type's arithmetic. Integer arithmetic is exact with a representability check at each step (out-of-range or non-exact division is an error); floating-point uses native float/double ops. Supports the 10 real-number data types this library models. The data type is unchanged; only the fill value is transformed and propagated downstream. Registered in the v3 CodecRegistry and exposed via CodecBuilder.withScaleOffset(...). Tests in the new dev.zarr.zarrjava.codec test package. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
konstibob
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Aug 4, 2026
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Here is a link for the specification https://github.com/zarr-developers/zarr-extensions/tree/main/codecs/scale_offset |
- Do not fail the codec pipeline when the fill value is not representable after the encode transformation. The fill value is metadata, not stored data, so an unsigned array with a fill value below the offset (e.g. uint16 with fill_value 0 and offset 1000) previously could not be created or opened at all. It is now kept untransformed in that case. - Reject a scale of 0 when the configuration is parsed. Encoding with a scale of 0 mapped every value to 0 without an error, while decoding either threw or produced NaN, so the data was unrecoverable. - Use long arithmetic with Math.*Exact and explicit bound checks for every integral type except uint64, instead of allocating several BigIntegers per array element, and skip the element-by-element rebuild entirely when neither offset nor scale is configured. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
normanrz
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Sep 4, 2026
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Should also be added to the userguide.
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Implemented the scale_offset array→array codec. Applies (in - offset) * scale on encode / (in / scale) + offset on decode, keeping dtype and shape unchanged.