[SPARK-8471] [ML] Rename DiscreteCosineTransformer to DCT

Rename DiscreteCosineTransformer and related classes to DCT.

Author: Feynman Liang <fliang@databricks.com>

Closes #7138 from feynmanliang/dct-features and squashes the following commits:

e547b3e [Feynman Liang] Fix renaming bug
9d5c9e4 [Feynman Liang] Lowercase JavaDCTSuite variable
f9a8958 [Feynman Liang] Remove old files
f8fe794 [Feynman Liang] Merge branch 'master' into dct-features
894d0b2 [Feynman Liang] Rename DiscreteCosineTransformer to DCT
433dbc7 [Feynman Liang] Test refactoring
91e9636 [Feynman Liang] Style guide and test helper refactor
b5ac19c [Feynman Liang] Use Vector types, add Java test
530983a [Feynman Liang] Tests for other numeric datatypes
195d7aa [Feynman Liang] Implement support for arbitrary numeric types
95d4939 [Feynman Liang] Working DCT for 1D Doubles

3 files changed, 8 insertions, 8 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/DiscreteCosineTransformer.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/DCT.scala
index a2f4d59f81..228347635c 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/DiscreteCosineTransformer.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/DCT.scala
@@ -36,8 +36,8 @@ import org.apache.spark.sql.types.DataType
  * More information on [[https://en.wikipedia.org/wiki/Discrete_cosine_transform#DCT-II Wikipedia]].
  */
 @Experimental
-class DiscreteCosineTransformer(override val uid: String)
-  extends UnaryTransformer[Vector, Vector, DiscreteCosineTransformer] {
+class DCT(override val uid: String)
+  extends UnaryTransformer[Vector, Vector, DCT] {
 
   def this() = this(Identifiable.randomUID("dct"))
 
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaDiscreteCosineTransformerSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaDCTSuite.java
index 28bc5f65e0..845eed61c4 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaDiscreteCosineTransformerSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaDCTSuite.java
@@ -37,13 +37,13 @@ import org.apache.spark.sql.types.Metadata;
 import org.apache.spark.sql.types.StructField;
 import org.apache.spark.sql.types.StructType;
 
-public class JavaDiscreteCosineTransformerSuite {
+public class JavaDCTSuite {
   private transient JavaSparkContext jsc;
   private transient SQLContext jsql;
 
   @Before
   public void setUp() {
-    jsc = new JavaSparkContext("local", "JavaDiscreteCosineTransformerSuite");
+    jsc = new JavaSparkContext("local", "JavaDCTSuite");
     jsql = new SQLContext(jsc);
   }
 
@@ -66,11 +66,11 @@ public class JavaDiscreteCosineTransformerSuite {
     double[] expectedResult = input.clone();
     (new DoubleDCT_1D(input.length)).forward(expectedResult, true);
 
-    DiscreteCosineTransformer DCT = new DiscreteCosineTransformer()
+    DCT dct = new DCT()
       .setInputCol("vec")
       .setOutputCol("resultVec");
 
-    Row[] result = DCT.transform(dataset).select("resultVec").collect();
+    Row[] result = dct.transform(dataset).select("resultVec").collect();
     Vector resultVec = result[0].getAs("resultVec");
 
     Assert.assertArrayEquals(expectedResult, resultVec.toArray(), 1e-6);
diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/DiscreteCosineTransformerSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/DCTSuite.scala
index ed0fc11f78..37ed2367c3 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/feature/DiscreteCosineTransformerSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/DCTSuite.scala
@@ -29,7 +29,7 @@ import org.apache.spark.sql.{DataFrame, Row}
 @BeanInfo
 case class DCTTestData(vec: Vector, wantedVec: Vector)
 
-class DiscreteCosineTransformerSuite extends SparkFunSuite with MLlibTestSparkContext {
+class DCTSuite extends SparkFunSuite with MLlibTestSparkContext {
 
   test("forward transform of discrete cosine matches jTransforms result") {
     val data = Vectors.dense((0 until 128).map(_ => 2D * math.random - 1D).toArray)
@@ -58,7 +58,7 @@ class DiscreteCosineTransformerSuite extends SparkFunSuite with MLlibTestSparkCo
       DCTTestData(data, expectedResult)
     ))
 
-    val transformer = new DiscreteCosineTransformer()
+    val transformer = new DCT()
       .setInputCol("vec")
       .setOutputCol("resultVec")
       .setInverse(inverse)