jaccard.sqlx

config { hasOutput: true }
/*
 * Copyright 2021 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

CREATE OR REPLACE FUNCTION ${self()}(a STRING, b STRING)
RETURNS FLOAT64
LANGUAGE js AS r"""
  let intersectSize = 0;

  if(a && b) {
    // Split word into characters, and make characters unique
    const sa = [...new Set(String(a).split(''))]
    const sb = [...new Set(String(b).split(''))]

    const la = sa.length;
    const lb = sb.length;

    for(let i = 0; i < la; i++) {
      for(let j = 0; j < lb; j++) {
        intersectSize += (sa[i] === sb[j]) ? 1 : 0
      }
    }

    // Compute Jaccard distance
    const union = (sa.length + sb.length) - intersectSize
    return parseFloat(((intersectSize / union) * 100 + Number.EPSILON) / 100).toFixed(2)
  } else {
    return 0.0
  }
""";