NEWS

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pizzarr 0.2.0 (2026-04-20)

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

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

pizzarr 0.1.2 (2026-04-06)

• 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 (2026-03-25)

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

pizzarr 0.1.0 (2026-03-24)

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.