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pizzarr 0.2.0-pre

Two-tier distribution

• CRAN ships pure R (no Rust compilation). r-universe ships pre-built binaries with the zarrs Rust backend compiled in. No Rust toolchain needed for end users on either tier.
• New functions: is_zarrs_available(), pizzarr_compiled_features(), pizzarr_upgrade().
• tools/cran-build.sh produces a CRAN tarball with src/ stripped out.

zarrs Rust backend (r-universe tier)

• Added zarrs Rust backend via extendr for parallel decompression, codec execution, and store abstraction. 9 #[extendr] functions, 13 Rust source files.
• Transparent dispatch: ZarrArray$get_item() and $set_item() automatically use the zarrs fast path when eligible (contiguous slices, supported dtype, filesystem or HTTP store). Unsupported selections fall through to the R-native path silently.
• Read path: two-step dtype dispatch retrieves data at stored precision, then widens to R-compatible types (f32→f64, i16→i32, etc.) in Rust before crossing the FFI boundary.
• Write path: symmetric narrowing with range checks (R double→f32, R integer→i16, etc.). Out-of-range values produce errors, not silent truncation.
• Array creation via zarrs: zarr_create() dispatches to the zarrs backend when available. Supports V2 and V3 formats with four codec presets (none, gzip, blosc, zstd).
• C↔︎F order transpose moved from R (aperm) to Rust, eliminating two full-array copies per read and up to five per write. Cache-blocked tiling for 2D, output-order iteration for nD.
• HTTP/HTTPS reads via zarrs_http crate. HttpStore-backed arrays use zarrs for parallel chunk decode on remote data. R-native crul-based path remains as fallback.
• S3 reads via object_store crate. New S3Store R6 class for s3:// URLs. Public buckets work without credentials (unsigned requests). Authenticated access uses standard AWS environment variables.
• GCS reads via object_store crate. New GcsStore R6 class for gs:// URLs (requires credentials). Public GCS data accessible via HTTPS endpoint without credentials.
• Process-global store handle cache with explicit lifecycle management via zarrs_close_store().

Configuration

• New pizzarr_config() function for viewing and setting concurrency options. Three settings: nthreads (rayon thread pool size), concurrent_target (codec concurrency level), and http_batch_range_requests (multipart range toggle for HTTP stores). All three backed by environment variables (PIZZARR_NTHREADS, PIZZARR_CONCURRENT_TARGET, PIZZARR_HTTP_BATCH_RANGE_REQUESTS).
• zarrs_runtime_info() now includes nthreads (rayon thread pool size).

Breaking changes

• Removed R-native parallel chunk I/O infrastructure. The pizzarr.parallel_backend, pizzarr.parallel_write_enabled, and pizzarr.progress_bar options are no longer used. On r-universe builds, zarrs handles parallelism internally via its Rust thread pool. On CRAN (pure R), chunk I/O is sequential.
• Dropped pbapply, parallel, future, and future.apply from Suggests.
• Removed vignettes/parallel.Rmd. Replaced by vignettes/zarrs-backend.Rmd.
• Minimum R version raised from 4.1.0 to 4.2.

Other changes

• New vignettes/zarrs-backend.Rmd documenting the zarrs backend, dispatch behavior, store types, concurrency tuning, and cloud access.
• R-native chunk loop simplified from parallel dispatch infrastructure to sequential for loop.

pizzarr 0.1.3 (never released)

• Added set_dimension_names() / get_dimension_names() methods to ZarrArray (#170).
• pkgdown site and documentation improvements (#171).

pizzarr 0.1.2

• Added get_dimension_names() method to ZarrArray for V3 dimension names support.
• OME-NGFF vignettes now use base R rasterImage() instead of the raster package (#161).

pizzarr 0.1.1

Fixes a flaky test failing on CRAN – no functional changes.

pizzarr 0.1.0

This is the first release of pizzarr to CRAN. The package has significant testing and validation but has not been vetted by a large and diverse user community. As a result, bugs and undesirable behavior may be found. If you find issues please report them at:

https://github.com/zarr-developers/pizzarr/issues

• Initial release of pizzarr.
• Read and write Zarr V2 and Zarr V3 stores.
• Storage backends: DirectoryStore, MemoryStore, HttpStore.
• Compression codecs: Zstd, LZ4, Blosc, zlib, gzip, bzip2, LZMA.
• VLenUTF8 object codec for variable-length strings.
• Parallel read/write support via pbapply, parallel, and future.
• R-like one-based and Python-like zero-based slicing.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
Health stats visible at Monitor.