{"id":16964993,"url":"https://github.com/propensive/metamorphose","last_synced_at":"2025-07-11T00:38:47.510Z","repository":{"id":246517963,"uuid":"821364109","full_name":"propensive/metamorphose","owner":"propensive","description":"Efficient permutation representations in Scala","archived":false,"fork":false,"pushed_at":"2025-01-26T12:15:06.000Z","size":578,"stargazers_count":3,"open_issues_count":0,"forks_count":0,"subscribers_count":1,"default_branch":"main","last_synced_at":"2025-07-04T22:48:36.762Z","etag":null,"topics":["combinatorics","factoriadic","factorials","lehmer","lehmer-codes","permutations"],"latest_commit_sha":null,"homepage":"https://soundness.dev/metamorphose/","language":"Scala","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/propensive.png","metadata":{"files":{"readme":".github/readme.md","changelog":null,"contributing":".github/contributing.md","funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null,"zenodo":null}},"created_at":"2024-06-28T11:25:43.000Z","updated_at":"2025-01-26T12:15:09.000Z","dependencies_parsed_at":"2024-08-15T14:47:04.479Z","dependency_job_id":"03bf0783-899c-4296-a070-27d272eca8fe","html_url":"https://github.com/propensive/metamorphose","commit_stats":null,"previous_names":["propensive/metamorphose"],"tags_count":17,"template":false,"template_full_name":null,"purl":"pkg:github/propensive/metamorphose","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fmetamorphose","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fmetamorphose/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fmetamorphose/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fmetamorphose/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/propensive","download_url":"https://codeload.github.com/propensive/metamorphose/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fmetamorphose/sbom","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":264697567,"owners_count":23650955,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["combinatorics","factoriadic","factorials","lehmer","lehmer-codes","permutations"],"created_at":"2024-10-13T23:44:47.244Z","updated_at":"2025-07-11T00:38:47.487Z","avatar_url":"https://github.com/propensive.png","language":"Scala","funding_links":[],"categories":[],"sub_categories":[],"readme":"[\u003cimg alt=\"GitHub Workflow\" src=\"https://img.shields.io/github/actions/workflow/status/propensive/metamorphose/main.yml?style=for-the-badge\" height=\"24\"\u003e](https://github.com/propensive/metamorphose/actions)\n[\u003cimg src=\"https://img.shields.io/discord/633198088311537684?color=8899f7\u0026label=DISCORD\u0026style=for-the-badge\" height=\"24\"\u003e](https://discord.com/invite/MBUrkTgMnA)\n\u003cimg src=\"/doc/images/github.png\" valign=\"middle\"\u003e\n\n# Metamorphose\n\n__Efficient permutation representations__\n\nA permutation is a rearrangement of the elements in an ordered collection. It\nis a one-to-one mapping—a bijection—and therefore reversible.\n[Lehmer codes](https://en.wikipedia.org/wiki/Lehmer_code) provide a mapping\nbetween positive integers and permutations, which make it possible to describe\na permutation of _n_ elements in _O(nlog(n))_ space. __Metamorphose__  provides\nan implementation of this encoding.\n\n## Features\n\n- efficient representation of permutations of collection elements\n- bijection between positive integers and permutations\n- provides a binary serialization of permutations\n\n\n## Availability\n\n\n\n\n\n\n\n## Getting Started\n\nMetamorphose primarily provides the `Permutation` class, which is in the\n`metamorphose` package and exported to the `soundness` package. You can import\nit with,\n```scala\nimport metamorphose.*\n```\nor,\n```scala\nimport soundness.*\n```\n\nThere are two ways to construct a new `Permutation`. Firstly, from an ordered\nsequence of distinct indexes, for example,\n```scala\nval permutation = Permutation(Vector(1, 4, 2, 3, 0))\n```\nwhich interprets the ordering of the indexes to yield the permutation with\nfactoradic number 45, i.e. `Permutation(Factoradic(45))`.\n\nOr, if we already know the factoradic number of the permutation, we can pass\nthat in directly, using the `Factoradic` costructor, like so:\n```scala\nval permutation = Permutation(Factoradic(45))\n```\n\nTo check that this is the same permutation, we can expand it with,\n```scala\nval order: List[Int] = permutation.expansion\n```\nwhich gives the original sequence back: `List(1, 4, 2, 3, 0)`.\n\nIt's also possible to see the Lehmer code derived from this permutation with,\n```scala\npermutation.lehmer\n```\nwhich produces, `List(1, 3, 1, 1, 0)`.\n\nWe can apply this permutation to a sufficiently long sequence just by applying\nit to the sequence, i.e. `permutation(list)`.\n\nPermutations are always reversible, and `Permutation#inverse` will construct a\nnew permutation which will permute a sequence permuted by the original\npermutation back to the original list.\n\nThat is, for all lists and permutations of the right size it is true that,\n```scala\npermutation.inverse(permutation(list)) == list\n```\n\n\n## Status\n\nMetamorphose is classified as __fledgling__. For reference, Soundness projects are\ncategorized into one of the following five stability levels:\n\n- _embryonic_: for experimental or demonstrative purposes only, without any guarantees of longevity\n- _fledgling_: of proven utility, seeking contributions, but liable to significant redesigns\n- _maturescent_: major design decisions broady settled, seeking probatory adoption and refinement\n- _dependable_: production-ready, subject to controlled ongoing maintenance and enhancement; tagged as version `1.0.0` or later\n- _adamantine_: proven, reliable and production-ready, with no further breaking changes ever anticipated\n\nProjects at any stability level, even _embryonic_ projects, can still be used,\nas long as caution is taken to avoid a mismatch between the project's stability\nlevel and the required stability and maintainability of your own project.\n\nMetamorphose is designed to be _small_. Its entire source code currently consists\nof 224 lines of code.\n\n## Building\n\nMetamorphose will ultimately be built by Fury, when it is published. In the\nmeantime, two possibilities are offered, however they are acknowledged to be\nfragile, inadequately tested, and unsuitable for anything more than\nexperimentation. They are provided only for the necessity of providing _some_\nanswer to the question, \"how can I try Metamorphose?\".\n\n1. *Copy the sources into your own project*\n   \n   Read the `fury` file in the repository root to understand Metamorphose's build\n   structure, dependencies and source location; the file format should be short\n   and quite intuitive. Copy the sources into a source directory in your own\n   project, then repeat (recursively) for each of the dependencies.\n\n   The sources are compiled against the latest nightly release of Scala 3.\n   There should be no problem to compile the project together with all of its\n   dependencies in a single compilation.\n\n2. *Build with [Wrath](https://github.com/propensive/wrath/)*\n\n   Wrath is a bootstrapping script for building Metamorphose and other projects in\n   the absence of a fully-featured build tool. It is designed to read the `fury`\n   file in the project directory, and produce a collection of JAR files which can\n   be added to a classpath, by compiling the project and all of its dependencies,\n   including the Scala compiler itself.\n   \n   Download the latest version of\n   [`wrath`](https://github.com/propensive/wrath/releases/latest), make it\n   executable, and add it to your path, for example by copying it to\n   `/usr/local/bin/`.\n\n   Clone this repository inside an empty directory, so that the build can\n   safely make clones of repositories it depends on as _peers_ of `metamorphose`.\n   Run `wrath -F` in the repository root. This will download and compile the\n   latest version of Scala, as well as all of Metamorphose's dependencies.\n\n   If the build was successful, the compiled JAR files can be found in the\n   `.wrath/dist` directory.\n\n## Contributing\n\nContributors to Metamorphose are welcome and encouraged. New contributors may like\nto look for issues marked\n[beginner](https://github.com/propensive/metamorphose/labels/beginner).\n\nWe suggest that all contributors read the [Contributing\nGuide](/contributing.md) to make the process of contributing to Metamorphose\neasier.\n\nPlease __do not__ contact project maintainers privately with questions unless\nthere is a good reason to keep them private. While it can be tempting to\nrepsond to such questions, private answers cannot be shared with a wider\naudience, and it can result in duplication of effort.\n\n## Author\n\nMetamorphose was designed and developed by Jon Pretty, and commercial support and\ntraining on all aspects of Scala 3 is available from [Propensive\nO\u0026Uuml;](https://propensive.com/).\n\n\n\n## Name\n\nWhen an insect metamorphoses, it permutes the elements of its body from one\nform into another.\n\nIn general, Soundness project names are always chosen with some rationale,\nhowever it is usually frivolous. Each name is chosen for more for its\n_uniqueness_ and _intrigue_ than its concision or catchiness, and there is no\nbias towards names with positive or \"nice\" meanings—since many of the libraries\nperform some quite unpleasant tasks.\n\nNames should be English words, though many are obscure or archaic, and it\nshould be noted how willingly English adopts foreign words. Names are generally\nof Greek or Latin origin, and have often arrived in English via a romance\nlanguage.\n\n## Logo\n\nThe logo shows a butterfly, which has undergone metamorphosis from a\ncaterpillar.\n\n## License\n\nMetamorphose is copyright \u0026copy; 2025 Jon Pretty \u0026 Propensive O\u0026Uuml;, and\nis made available under the [Apache 2.0 License](/license.md).\n\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpropensive%2Fmetamorphose","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fpropensive%2Fmetamorphose","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpropensive%2Fmetamorphose/lists"}