Github user MLnick commented on a diff in the pull request:
https://github.com/apache/spark/pull/15148#discussion_r80477078
--- Diff:
mllib/src/main/scala/org/apache/spark/ml/feature/lsh/MinHash.scala ---
@@ -0,0 +1,94 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+package org.apache.spark.ml.feature.lsh
+
+import scala.util.Random
+
+import org.apache.spark.ml.linalg.{Vector, Vectors}
+import org.apache.spark.ml.param.{IntParam, Params, ParamValidators}
+import org.apache.spark.ml.util.Identifiable
+import org.apache.spark.sql.Dataset
+
+/**
+ * Params for [[MinHash]].
+ */
+private[ml] trait MinHashModelParams extends Params {
+ protected[this] val prime = 2038074743
+
+ val numIndex: IntParam = new IntParam(this, "numIndex", "the number of
index",
+ ParamValidators.inRange(0, prime, lowerInclusive = false,
upperInclusive = false))
+}
+
+class MinHashModel(override val uid: String, hashFunctions: Seq[Double =>
Double])
+ extends LSHModel[Seq[Double], MinHashModel] with MinHashModelParams {
+
+ override protected[this] val hashFunction: Seq[Double] => Vector = {
+ elems: Seq[Double] =>
+ Vectors.dense(hashFunctions.map(
+ func => elems.map(func).min
+ ).toArray)
+ }
+
+ /**
+ * :: DeveloperApi ::
+ *
+ * Calculate the distance between two different keys using the distance
metric corresponding
+ * to the hashFunction
+ *
+ * @param x One of the point in the metric space
+ * @param y Another the point in the metric space
+ * @return The distance between x and y in double
+ */
+ override protected[ml] def keyDistance(x: Seq[Double], y: Seq[Double]):
Double = {
+ val xSet = x.toSet
+ val ySet = y.toSet
+ 1 - xSet.intersect(ySet).size.toDouble / xSet.union(ySet).size.toDouble
+ }
+}
+
+/**
+ * LSH class for Jaccard distance
+ * @param uid
+ */
+class MinHash(override val uid: String) extends LSH[Seq[Double],
MinHashModel]
+ with MinHashModelParams {
+
+ private[this] lazy val randSeq: Seq[Int] = {
+ Seq.fill($(outputDim))(1 + Random.nextInt(prime -
1)).take($(outputDim))
+ }
+
+ private[this] lazy val hashFunctions: Seq[Double => Double] = {
--- End diff --
While not a hard style requirement, most of the codebase prefers this
style:
```scala
private[this] lazy val hashFunctions: Seq[Double => Double] = {
(0 until $(outputDim)).map { i =>
// Perfect Hash function, use 2n buckets to reduce collision.
elem: Double => (1 + elem) * randSeq(i).toLong % prime % ($(numIndex)
* 2)
}
}
```
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
