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zarr-python

Category: data-science-and-ml · License: MIT · Version: 1.3 Tags: Zarr, chunked arrays, cloud storage, N-dimensional data, scientific data

When to use it

Guides use of Zarr-Python 3 for storing chunked, compressed N-dimensional arrays and groups, with local, in-memory, ZIP, and fsspec-backed S3/GCS/HTTP stores, plus NumPy, Dask, and Xarray integration. Covers array creation, resizing and appending, attributes, chunk and shard sizing, codecs, consolidated metadata, and v2-to-v3 migration. Use when creating or opening Zarr arrays or groups, choosing chunk sizes or compression for large datasets, reading or writing arrays on S3 or GCS, appending to time-series arrays, or migrating code from Zarr-Python 2 to 3. Use when setting up parallel I/O with Dask or Xarray. For labeled multi-dimensional datasets, use Xarray instead.

Example requests

Ask your agent in plain language, for example:
  • “How do I append new rows to a zarr array as data comes in?”
  • “I’m upgrading our pipeline in ingest/store_frames.py from zarr 2.16 to the latest release. I’m now getting AttributeError: 'Group' object has no attribute 'create_dataset' and zarr.open(..., mode='a') behaves differently with my old .zarr directory made with DirectoryStore. What changed and how do I fix it?”
  • “I have a 2 TB stack of microscopy images (T x Z x Y x X, uint16) sitting in a bucket on S3. I want to convert it into something that many Dask workers can read slices from in parallel without downloading everything, and compression should keep storage costs down. How should I lay this out?”

Install

In Claude Code you can also add the marketplace with /plugin marketplace add KalarisLabs/research-agent-skills and install the whole data-science-and-ml category with /plugin install data-science-and-ml@research-agent-skills.

Full playbook

Read SKILL.md for the complete workflow, references and any scripts. The agent installer copies the full skill folder.
Last modified on October 19, 2026