add test

mllib/src/test/scala/org/apache/spark/ml/fpm/PrefixSpanSuite.scala

@@ -0,0 +1,100 @@
+/*
+ * 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.fpm
+
+import org.apache.spark.ml.util.MLTest
+import org.apache.spark.sql.DataFrame
+
+class PrefixSpanSuite extends MLTest {
+
+  import testImplicits._
+
+  override def beforeAll(): Unit = {
+    super.beforeAll()
+    smallDataset = Seq(Seq(Seq(1, 2), Seq(1, 2, 3))).toDF("sequence")
+  }
+
+  @transient var smallDataset: DataFrame = _
+
+  test("PrefixSpan projections with multiple partial starts") {
+    val result = PrefixSpan.findFrequentSequentPatterns(smallDataset, "sequence",
+      minSupport = 1.0, maxPatternLength = 2).as[(Seq[Seq[Int]], Long)].collect()
+    val expected = Array(
+      (Seq(Seq(1)), 1L),
+      (Seq(Seq(1, 2)), 1L),
+      (Seq(Seq(1), Seq(1)), 1L),
+      (Seq(Seq(1), Seq(2)), 1L),
+      (Seq(Seq(1), Seq(3)), 1L),
+      (Seq(Seq(1, 3)), 1L),
+      (Seq(Seq(2)), 1L),
+      (Seq(Seq(2, 3)), 1L),
+      (Seq(Seq(2), Seq(1)), 1L),
+      (Seq(Seq(2), Seq(2)), 1L),
+      (Seq(Seq(2), Seq(3)), 1L),
+      (Seq(Seq(3)), 1L))
+    compareResults[Int](expected, result)
+  }
+
+  val smallTestData = Seq(
+    Seq(Seq(1, 2), Seq(3)),
+    Seq(Seq(1), Seq(3, 2), Seq(1, 2)),
+    Seq(Seq(1, 2), Seq(5)),
+    Seq(Seq(6)))
+
+  val smallTestDataExpectedResult = Array(
+    (Seq(Seq(1)), 3L),
+    (Seq(Seq(2)), 3L),
+    (Seq(Seq(3)), 2L),
+    (Seq(Seq(1), Seq(3)), 2L),
+    (Seq(Seq(1, 2)), 3L)
+  )
+
+  test("PrefixSpan Integer type, variable-size itemsets") {
+    val df = smallTestData.toDF("sequence")
+    val result = PrefixSpan.findFrequentSequentPatterns(df, "sequence",
+      minSupport = 0.5, maxPatternLength = 5).as[(Seq[Seq[Int]], Long)].collect()
+
+    compareResults[Int](smallTestDataExpectedResult, result)
+  }
+
+  test("PrefixSpan String type, variable-size itemsets") {
+    val intToString = (1 to 6).zip(Seq("a", "b", "c", "d", "e", "f")).toMap
+    val df = smallTestData
+      .map(seq => seq.map(itemSet => itemSet.map(intToString)))
+      .toDF("sequence")
+    val result = PrefixSpan.findFrequentSequentPatterns(df, "sequence",
+      minSupport = 0.5, maxPatternLength = 5).as[(Seq[Seq[String]], Long)].collect()
+
+    val expected = smallTestDataExpectedResult.map { case (seq, freq) =>
+      (seq.map(itemSet => itemSet.map(intToString)), freq)
+    }
+    compareResults[String](expected, result)
+  }
+
+  private def compareResults[Item](
+      expectedValue: Array[(Seq[Seq[Item]], Long)],
+      actualValue: Array[(Seq[Seq[Item]], Long)]): Unit = {
+    val expectedSet = expectedValue.map { x =>
+      (x._1.map(_.toSet), x._2)
+    }.toSet
+    val actualSet = actualValue.map { x =>
+      (x._1.map(_.toSet), x._2)
+    }.toSet
+    assert(expectedSet === actualSet)
+  }
+}
+