Linear Regression Model inference with Painless in ElasticSearch

painless_linear_regression.json

PUT _scripts/linear_regression_inference
{
  "script": {
    "lang": "painless",
    "source": """
    double total = params.intercept;
    for (int i = 0; i < params.coefs.length; ++i) {
      total += params.coefs.get(i) * doc[params['x'+i]].value;
    }
    return total;
    """
  }
}

Example:
GET diabetes_test/_search
{
  "script_fields": {
    "regression_score": {
      "script": {
        "id": "linear_regression_inference",
        "params": {
          "coefs": [-35.55683674, -243.1692265, 562.75404632, 305.47203008, -662.78772128, 324.27527477, 24.78193291, 170.33056502, 731.67810787, 43.02846824],
          "intercept": 152.53813351954059,
          "x0": "age",
          "x1": "sex",
          "x2": "bmi",
          "x3": "bp",
          "x4": "s1",
          "x5": "s2",
          "x6": "s3",
          "x7": "s4",
          "x8": "s5",
          "x9": "s6"
        }
      }
    }
  }
}

>{
  "took" : 12,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : 89,
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "diabetes_test",
        "_type" : "_doc",
        "_id" : "CbwAWmkBea2J_i2W7BYc",
        "_score" : 1.0,
        "fields" : {
          "regression_score" : [
            248.93170645607083
          ]
        }
      },...
      ]