{"id":14973990,"url":"https://github.com/palestamp/hamming_distance","last_synced_at":"2025-10-27T05:31:20.169Z","repository":{"id":239035401,"uuid":"66362961","full_name":"palestamp/hamming_distance","owner":"palestamp","description":"Hamming distance extension for Postgres.","archived":false,"fork":false,"pushed_at":"2017-07-04T22:26:36.000Z","size":5,"stargazers_count":6,"open_issues_count":0,"forks_count":1,"subscribers_count":2,"default_branch":"master","last_synced_at":"2025-02-01T02:41:22.791Z","etag":null,"topics":["c","hamming-distance","pgsql","postgresql"],"latest_commit_sha":null,"homepage":"","language":"C","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/palestamp.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","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}},"created_at":"2016-08-23T11:59:08.000Z","updated_at":"2024-11-18T14:59:16.000Z","dependencies_parsed_at":"2024-05-09T16:27:34.850Z","dependency_job_id":"393b0f2c-196c-495c-a427-5fc4c4a84a3f","html_url":"https://github.com/palestamp/hamming_distance","commit_stats":null,"previous_names":["palestamp/hamming_distance"],"tags_count":0,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/palestamp%2Fhamming_distance","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/palestamp%2Fhamming_distance/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/palestamp%2Fhamming_distance/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/palestamp%2Fhamming_distance/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/palestamp","download_url":"https://codeload.github.com/palestamp/hamming_distance/tar.gz/refs/heads/master","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":238445830,"owners_count":19473820,"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":["c","hamming-distance","pgsql","postgresql"],"created_at":"2024-09-24T13:49:47.527Z","updated_at":"2025-10-27T05:31:19.839Z","avatar_url":"https://github.com/palestamp.png","language":"C","readme":"Hex-Pair Hamming Distance Functions\n===================================\nThis extension provides four functions to work with hex representation of \nfeature vector.\n\n    \n\nEvery function asserts that both arguments have the same length.\n\n\n\n### hamming_distance(varchar, varchar) RETURNS int (IMMUTABLE STRICT)\n\nComputes absolute hamming distance between to FVs\n\n    SELECT hamming_distance('1d3f', '1110');\n     hamming_distance\n    ------------------\n                    7\n    (1 row)\n\nThis expands as\n\n    a = '1d3f'  -\u003e 0001 1101 0011 1111\n    b = '1110'  -\u003e 0001 0001 0001 0000\n \n    c = a ^ b   -\u003e 0000 1100 0010 1111\n\n    popcount(c) -\u003e   0 + 2 + 1 + 4 = 7\n    \n\n### hamming_similarity(varchar, varchar) RETURNS int (IMMUTABLE STRICT)\n\n    SELECT hamming_similarity('1d3f', '1110');\n     hamming_similarity\n    --------------------\n                      9\n    (1 row)\n\nCan be defined as\n    \n    HAMMING_SIMILARITY = len(a) * 4 - hamming_distance(a, b);\n\n\n### hamming_distance_normalized(varchar, varchar) RETURNS float (IMMUTABLE STRICT)\n\n    SELECT hamming_distance_normalized('1d3f', '1110');\n     hamming_distance_normalized\n    -----------------------------\n                          0.4375\n    (1 row)\n\nCan be defined as\n    \n    HAMMING_DISTANCE_NORM = hamming_distance(a, b) / len(a) * 4;\n\n\n### hamming_similarity_normalized(varchar, varchar) RETURNS float (IMMUTABLE STRICT)\n\n    SELECT hamming_similarity_normalized('1d3f', '1110');\n     hamming_similarity_normalized\n    -------------------------------\n                            0.5625\n    (1 row)\n\nCan be defined as\n    \n    HAMMING_SIMILARITY_NORM = hamming_similarity(a, b) / len(a) * 4;\n\n\nInstallation\n============\n\n    cd .../hamming_distance\n    sudo make install\n\n\nRunning tests\n=============\n    \n    make installcheck \n","funding_links":[],"categories":[],"sub_categories":[],"project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpalestamp%2Fhamming_distance","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fpalestamp%2Fhamming_distance","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpalestamp%2Fhamming_distance/lists"}