Cookbook

Simple recipes for using zarrita.

Open an Array v2 & v3

import * as zarr from "zarrita";

const store = new zarr.FetchStore("http://localhost:8080/data.zarr");
const arr = await zarr.open(store, { kind: "array" });
arr; // zarr.Array<DataType, FetchStore>
arr.shape; // [5, 10]
arr.chunks; // [2, 5]
arr.dtype; // "int32"

Open a Group v2 & v3

import * as zarr from "zarrita";

const store = new zarr.FetchStore("http://localhost:8080/data.zarr");
const group = await zarr.open(store, { kind: "group" });
group; // zarr.Group

Open a Group or Array v2 & v3

import * as zarr from "zarrita";

const store = new zarr.FetchStore("http://localhost:8080/data.zarr");
const node = await zarr.open(store);
node; // zarr.Array<DataType, FetchStore> | zarr.Group

Open a Group or an Array from another Node v2 & v3

import * as zarr from "zarrita";

const store = new zarr.FetchStore("http://localhost:8080/data.zarr");
const node = await zarr.open(store);
const arr = await zarr.open(node.resolve("path/to/foo"), { kind: "array" });

Open Array or Group with strict version v2 & v3

You can enforce version with open.v2 or open.v3 respectively.

import * as zarr from "zarrita";

const store = new zarr.FetchStore("http://localhost:8080/data.zarr");
const arr = await zarr.open.v2(store, { kind: "array" });

Create an Array v3

Requires the store to implement Writable.

import * as zarr from "zarrita";
import { FileSystemStore } from "@zarrita/storage";

const store = new FileSystemStore("tempstore");
const arr = await zarr.create(store, {
	shape: [10, 10],
	chunks: [5, 5],
	dtype: "int32",
});
arr; // zarr.Array<"int32", FileSystemStore>

Create a Group v3

Requires the store to implement Writable.

import * as zarr from "zarrita";
import { FileSystemStore } from "@zarrita/storage";

const store = new FileSystemStore("tempstore");
const group = await zarr.create(store, {
	attributes: { answer: 42 },
});
group; // zarr.Group

Open a Consolidated Store

Zarr v2 allows consolidating metadata for an entire hierarchy at the store root (under /.zmetadata). Metadata consolidation is particularly useful when interacting with remote stores, where each metadata fetch incurs a network request and hence, latency.

The withConsolidated helper wraps an existing store, proxying metadata requests with the consolidated metadata, thereby minimizing network requests.

import * as zarr from "zarrita";

let store = await zarr.withConsolidated(
	new zarr.FetchStore("https://localhost:8080/data.zarr")
);

// The following do not incur network requests for metadata
let root = await zarr.open(store, { kind: "group" });
let foo = await zarr.open(root.resolve("foo"), { kind: "array" });

The store returned from withConsolidated is readonly and adds .contents() list the known contents of the hierarchy:

store.contents(); // [{ path: "/", kind: "group" }, { path: "/foo", kind: "array" }, ...]

TIP

The withConsolidated helper errors out if v2 consolidated metadata is absent. Use tryWithConsolidated for uncertain cases; it leverages consolidated metadata if available.

let store = await zarr.tryWithConsolidated(
	new zarr.FetchStore("https://localhost:8080/data.zarr"),
);