[SPARK-8051] [MLLIB] make StringIndexerModel silent if input column does not exist

This is just a workaround to a bigger problem. Some pipeline stages may not be effective during prediction, and they should not complain about missing required columns, e.g. `StringIndexerModel`. jkbradley

Author: Xiangrui Meng <meng@databricks.com>

Closes #6595 from mengxr/SPARK-8051 and squashes the following commits:

b6a36b9 [Xiangrui Meng] add doc
f143fd4 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-8051
8ee7c7e [Xiangrui Meng] use SparkFunSuite
e112394 [Xiangrui Meng] make StringIndexerModel silent if input column does not exist

1 files changed, 8 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 cbf1e8ddcb..5f557e16e5 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
@@ -60,4 +60,12 @@ class StringIndexerSuite extends SparkFunSuite with MLlibTestSparkContext {
     val expected = Set((0, 0.0), (1, 2.0), (2, 1.0), (3, 0.0), (4, 0.0), (5, 1.0))
     assert(output === expected)
   }
+
+  test("StringIndexerModel should keep silent if the input column does not exist.") {
+    val indexerModel = new StringIndexerModel("indexer", Array("a", "b", "c"))
+      .setInputCol("label")
+      .setOutputCol("labelIndex")
+    val df = sqlContext.range(0L, 10L)
+    assert(indexerModel.transform(df).eq(df))
+  }
 }