Stats Extension Specification

• Title: Stats
• Identifier: https://stac-extensions.github.io/stats/v0.2.0/schema.json
• Field Name Prefix: stats
• Scope: Catalog, Collection
• Extension Maturity Classification: Pilot
• Owner: @tschaub

This document explains the Stats Extension to the SpatioTemporal Asset Catalog (STAC) specification.

Catalogs and collections using this extension include additional information summarizing the resource types included. Top-level catalogs can report counts of child catalogs, collections, or items and can include information on the versions, extensions, and asset types (in the case of items) used by those resources. Collections or sub-catalogs can also report statistics on child resources instead of having this reported at the top level.

• Examples:
  • Catalog with all stats: Shows the usage of the extension in a top-level Catalog
  • Collection with item stats: Shows the usage of the extension in a Collection (instead of at the top-level Catalog)
• JSON Schema
• Changelog

Top-Level Catalog or Collection Fields

Field Name	Type	Description
stats:catalogs	Catalogs Stats	A lookup of stats for all child catalogs.
stats:collections	Collections Stats	A lookup of stats for all child collections.
stats:items	Items Stats	A lookup of stats for all child items.

Catalogs Stats

Information about the resources included in all child catalogs.

Field Name	Type	Description
count	number	REQUIRED. The count of all child catalogs.
versions	object	A lookup of counts for all versions. Keys are version identifiers, and values are integer counts.
extensions	object	A lookup of counts for all extensions. Keys are extension identifiers, and values are integer counts.
conformance	object	A lookup of counts for STAC API conformance classes. Keys are conformance URIs, and values are integer counts.

Example stats:catalogs that might be found in a top-level catalog with three child sub-catalogs.

{
  "stats:catalogs": {
    "count": 3,
    "versions": {
      "1.0.0": 1,
      "1.0.0-beta.2": 2
    }
  }
}

Collections Stats

Information about the resources included in all child collections.

Field Name	Type	Description
count	number	REQUIRED. The count of all child collections.
versions	object	A lookup of counts for all versions. Keys are version identifiers, and values are integer counts.
extensions	object	A lookup of counts for all extensions. Keys are extension identifiers, and values are integer counts.

Example stats:collections that might be found in a top-level catalog with four child collections (two of which use an extension).

{
  "stats:collections": {
    "count": 4,
    "versions": {
      "1.0.0": 4
    },
    "extensions": {
      "https://stac-extensions.github.io/eo/v1.0.0/schema.json": 2
    }
  }
}

Items Stats

Information about the resources included in all child items.

Field Name	Type	Description
count	number	REQUIRED. The count of all child items.
versions	object	A lookup of counts for all versions. Keys are version identifiers, and values are integer counts.
extensions	object	A lookup of counts for all extensions. Keys are extension identifiers, and values are integer counts.
assets	object	A lookup of counts for all assets. Keys are asset types, and values are integer counts.

Example stats:items that might be found in a collection with 100 items.

{
  "stats:items": {
    "count": 100,
    "versions": {
      "1.0.0-beta.2": 20,
      "1.0.0": 80
    },
    "extensions": {
      "https://stac-extensions.github.io/eo/v1.0.0/schema.json": 80,
      "https://stac-extensions.github.io/raster/v1.0.0/schema.json": 50
    },
    "assets": {
      "image/jpeg": 20,
      "image/png": 30,
      "image/tiff; application=geotiff; profile=cloud-optimized": 50
    }
  }
}

Contributing

All contributions are subject to the STAC Specification Code of Conduct. For contributions, please follow the STAC specification contributing guide Instructions for running tests are copied here for convenience.

Running tests

The same checks that run as checks on PR's are part of the repository and can be run locally to verify that changes are valid. To run tests locally, you'll need npm, which is a standard part of any node.js installation.

First you'll need to install everything with npm once. Just navigate to the root of this repository and on your command line run:

npm install

Then to check markdown formatting and test the examples against the JSON schema, you can run:

npm test

This will spit out the same texts that you see online, and you can then go and fix your markdown or examples.

If the tests reveal formatting problems with the examples, you can fix them with:

npm run format-examples