[SPARK-8764] [ML] string indexer should take option to handle unseen values

As a precursor to adding a public constructor add an option to handle unseen values by skipping rather than throwing an exception (default remains throwing an exception),

Author: Holden Karau <holden@pigscanfly.ca>

Closes #7266 from holdenk/SPARK-8764-string-indexer-should-take-option-to-handle-unseen-values and squashes the following commits:

38a4de9 [Holden Karau] fix long line
045bf22 [Holden Karau] Add a second b entry so b gets 0 for sure
81dd312 [Holden Karau] Update the docs for handleInvalid param to be more descriptive
7f37f6e [Holden Karau] remove extra space (scala style)
414e249 [Holden Karau] And switch to using handleInvalid instead of skipInvalid
1e53f9b [Holden Karau] update the param (codegen side)
7a22215 [Holden Karau] fix typo
100a39b [Holden Karau] Merge in master
aa5b093 [Holden Karau] Since we filter we should never go down this code path if getSkipInvalid is true
75ffa69 [Holden Karau] Remove extra newline
d69ef5e [Holden Karau] Add a test
b5734be [Holden Karau] Add support for unseen labels
afecd4e [Holden Karau] Add a param to skip invalid entries.

1 files changed, 32 insertions, 0 deletions

diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala
index d0295a0fe2..b111036087 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala
@@ -17,6 +17,7 @@
 
 package org.apache.spark.ml.feature
 
+import org.apache.spark.SparkException
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.ml.attribute.{Attribute, NominalAttribute}
 import org.apache.spark.ml.param.ParamsSuite
@@ -62,6 +63,37 @@ class StringIndexerSuite extends SparkFunSuite with MLlibTestSparkContext {
       reversed2.collect().map(r => (r.getInt(0), r.getString(1))).toSet)
   }
 
+  test("StringIndexerUnseen") {
+    val data = sc.parallelize(Seq((0, "a"), (1, "b"), (4, "b")), 2)
+    val data2 = sc.parallelize(Seq((0, "a"), (1, "b"), (2, "c")), 2)
+    val df = sqlContext.createDataFrame(data).toDF("id", "label")
+    val df2 = sqlContext.createDataFrame(data2).toDF("id", "label")
+    val indexer = new StringIndexer()
+      .setInputCol("label")
+      .setOutputCol("labelIndex")
+      .fit(df)
+    // Verify we throw by default with unseen values
+    intercept[SparkException] {
+      indexer.transform(df2).collect()
+    }
+    val indexerSkipInvalid = new StringIndexer()
+      .setInputCol("label")
+      .setOutputCol("labelIndex")
+      .setHandleInvalid("skip")
+      .fit(df)
+    // Verify that we skip the c record
+    val transformed = indexerSkipInvalid.transform(df2)
+    val attr = Attribute.fromStructField(transformed.schema("labelIndex"))
+      .asInstanceOf[NominalAttribute]
+    assert(attr.values.get === Array("b", "a"))
+    val output = transformed.select("id", "labelIndex").map { r =>
+      (r.getInt(0), r.getDouble(1))
+    }.collect().toSet
+    // a -> 1, b -> 0
+    val expected = Set((0, 1.0), (1, 0.0))
+    assert(output === expected)
+  }
+
   test("StringIndexer with a numeric input column") {
     val data = sc.parallelize(Seq((0, 100), (1, 200), (2, 300), (3, 100), (4, 100), (5, 300)), 2)
     val df = sqlContext.createDataFrame(data).toDF("id", "label")