diff --git a/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoder.java b/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoder.java
index 5d5933f6d2f..600b6989eb8 100644
--- a/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoder.java
+++ b/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoder.java
@@ -166,7 +166,7 @@ protected void applySparse(CacheBlock in, MatrixBlock out, int outputCol, int ro
 			out.quickSetValue(i, outputCol, getCode(in, i));
 		}
 	}*/
-	
+
 	protected void applyDense(CacheBlock in, MatrixBlock out, int outputCol, int rowStart, int blk){
 		// Apply loop tiling to exploit CPU caches
 		double[] codes = getCodeCol(in, rowStart, blk);
@@ -343,7 +343,7 @@ public Callable<Object> getBuildTask(CacheBlock in) {
 		throw new DMLRuntimeException("Trying to get the Build task of an Encoder which does not require building");
 	}
 
-	public Callable<Object> getPartialBuildTask(CacheBlock in, int startRow, 
+	public Callable<Object> getPartialBuildTask(CacheBlock in, int startRow,
 			int blockSize, HashMap<Integer, Object> ret) {
 		throw new DMLRuntimeException(
 			"Trying to get the PartialBuild task of an Encoder which does not support  partial building");
@@ -409,7 +409,7 @@ protected void setApplyRowBlocksPerColumn(int nPart) {
 	}
 
 	public enum EncoderType {
-		Recode, FeatureHash, PassThrough, Bin, Dummycode, Omit, MVImpute, Composite
+		Recode, FeatureHash, PassThrough, Bin, Dummycode, Omit, MVImpute, Composite, Udf
 	}
 
 	/*
diff --git a/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoderUDF.java b/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoderUDF.java
index 114eb5f8efe..01c21e19169 100644
--- a/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoderUDF.java
+++ b/src/main/java/org/apache/sysds/runtime/transform/encode/ColumnEncoderUDF.java
@@ -6,9 +6,9 @@
  * 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
@@ -19,6 +19,9 @@
 
 package org.apache.sysds.runtime.transform.encode;
 
+import java.io.IOException;
+import java.io.ObjectInput;
+import java.io.ObjectOutput;
 import java.util.List;
 
 import org.apache.sysds.api.DMLScript;
@@ -45,8 +48,8 @@ public class ColumnEncoderUDF extends ColumnEncoder {
 
 	//TODO pass execution context through encoder factory for arbitrary functions not just builtin
 	//TODO integration into IPA to ensure existence of unoptimized functions
-	
-	private final String _fName;
+
+	private String _fName;
 	public int _domainSize = 1;
 
 	protected ColumnEncoderUDF(int ptCols, String name) {
@@ -72,7 +75,7 @@ public void build(CacheBlock in) {
 	public List<DependencyTask<?>> getBuildTasks(CacheBlock in) {
 		return null;
 	}
-	
+
 	@Override
 	public void applyDense(CacheBlock in, MatrixBlock out, int outputCol, int rowStart, int blk) {
 		long t0 = DMLScript.STATISTICS ? System.nanoTime() : 0;
@@ -82,7 +85,7 @@ public void applyDense(CacheBlock in, MatrixBlock out, int outputCol, int rowSta
 		MatrixBlock col = out.slice(0, in.getNumRows()-1, outputCol, outputCol+_domainSize-1, new MatrixBlock());
 		ec.setVariable("I", new ListObject(new Data[] {ParamservUtils.newMatrixObject(col, true)}));
 		ec.setVariable("O", ParamservUtils.newMatrixObject(col, true));
-		
+
 		//call UDF function via eval machinery
 		var fun = new EvalNaryCPInstruction(null, "eval", "",
 			new CPOperand("O", ValueType.FP64, DataType.MATRIX),
@@ -93,9 +96,6 @@ public void applyDense(CacheBlock in, MatrixBlock out, int outputCol, int rowSta
 
 		//obtain result and in-place write back
 		MatrixBlock ret = ((MatrixObject)ec.getCacheableData("O")).acquireReadAndRelease();
-		//out.leftIndexingOperations(ret, 0, in.getNumRows()-1, _colID-1, _colID-1, ret, UpdateType.INPLACE);
-		//out.leftIndexingOperations(ret, 0, in.getNumRows()-1, outputCol, outputCol+_domainSize-1, ret, UpdateType.INPLACE);
-		//out.copy(0, in.getNumRows()-1, _colID-1, _colID-1, ret, true);
 		out.copy(0, in.getNumRows()-1, outputCol, outputCol+_domainSize-1, ret, true);
 
 		if (DMLScript.STATISTICS)
@@ -124,14 +124,14 @@ else if(columnEncoder instanceof ColumnEncoderFeatureHash){
 			}
 		}
 	}
-	
+
 	@Override
 	protected ColumnApplyTask<ColumnEncoderUDF> getSparseTask(CacheBlock in,
 		MatrixBlock out, int outputCol, int startRow, int blk)
 	{
 		throw new DMLRuntimeException("UDF encoders do not support sparse tasks.");
 	}
-	
+
 	@Override
 	public void mergeAt(ColumnEncoder other) {
 		if(other instanceof ColumnEncoderUDF)
@@ -165,4 +165,21 @@ protected double getCode(CacheBlock in, int row) {
 	protected double[] getCodeCol(CacheBlock in, int startInd, int blkSize) {
 		throw new DMLRuntimeException("UDF encoders only support full column access.");
 	}
+
+	@Override
+	public void writeExternal(ObjectOutput out) throws IOException {
+		LOG.debug("Writing ColumnEncoderUTF to create");
+		super.writeExternal(out);
+		out.writeInt(_domainSize);
+		out.writeUTF(_fName);
+	}
+
+	@Override
+	public void readExternal(ObjectInput in) throws IOException {
+		LOG.debug("reading ColumnEncoderUTF");
+		super.readExternal(in);
+		_domainSize = in.readInt();
+		_fName = in.readUTF();
+		LOG.debug("set _fName: " + _fName);
+	}
 }
diff --git a/src/main/java/org/apache/sysds/runtime/transform/encode/EncoderFactory.java b/src/main/java/org/apache/sysds/runtime/transform/encode/EncoderFactory.java
index f76a83e3623..9105ff79150 100644
--- a/src/main/java/org/apache/sysds/runtime/transform/encode/EncoderFactory.java
+++ b/src/main/java/org/apache/sysds/runtime/transform/encode/EncoderFactory.java
@@ -93,7 +93,7 @@ public static MultiColumnEncoder createEncoder(String spec, String[] colnames, V
 			List<Integer> mvIDs = Arrays.asList(ArrayUtils.toObject(
 				TfMetaUtils.parseJsonObjectIDList(jSpec, colnames, TfMethod.IMPUTE.toString(), minCol, maxCol)));
 			List<Integer> udfIDs = TfMetaUtils.parseUDFColIDs(jSpec, colnames, minCol, maxCol);
-			
+
 			// create individual encoders
 			if(!rcIDs.isEmpty())
 				for(Integer id : rcIDs)
@@ -104,7 +104,7 @@ public static MultiColumnEncoder createEncoder(String spec, String[] colnames, V
 			if(!ptIDs.isEmpty())
 				for(Integer id : ptIDs)
 					addEncoderToMap(new ColumnEncoderPassThrough(id), colEncoders);
-			
+
 			if(!binIDs.isEmpty())
 				for(Object o : (JSONArray) jSpec.get(TfMethod.BIN.toString())) {
 					JSONObject colspec = (JSONObject) o;
@@ -131,7 +131,7 @@ else if ("EQUI-HEIGHT".equals(method))
 				for(Integer id : udfIDs)
 					addEncoderToMap(new ColumnEncoderUDF(id, name), colEncoders);
 			}
-			
+
 			// create composite decoder of all created encoders
 			for(Entry<Integer, List<ColumnEncoder>> listEntry : colEncoders.entrySet()) {
 				if(DMLScript.STATISTICS)
@@ -189,8 +189,8 @@ private static void addEncoderToMap(ColumnEncoder encoder, HashMap<Integer, List
 	}
 
 	public static int getEncoderType(ColumnEncoder columnEncoder) {
-		//TODO replace with columnEncoder.getType().ordinal
-		//(which requires a cleanup of all type handling)
+		// TODO replace with columnEncoder.getType().ordinal
+		// (which requires a cleanup of all type handling)
 		if(columnEncoder instanceof ColumnEncoderBin)
 			return EncoderType.Bin.ordinal();
 		else if(columnEncoder instanceof ColumnEncoderDummycode)
@@ -201,6 +201,8 @@ else if(columnEncoder instanceof ColumnEncoderPassThrough)
 			return EncoderType.PassThrough.ordinal();
 		else if(columnEncoder instanceof ColumnEncoderRecode)
 			return EncoderType.Recode.ordinal();
+		else if(columnEncoder instanceof ColumnEncoderUDF)
+			return EncoderType.Udf.ordinal();
 		throw new DMLRuntimeException("Unsupported encoder type: " + columnEncoder.getClass().getCanonicalName());
 	}
 
@@ -217,6 +219,8 @@ public static ColumnEncoder createInstance(int type) {
 				return new ColumnEncoderPassThrough();
 			case Recode:
 				return new ColumnEncoderRecode();
+			case Udf:
+				return new ColumnEncoderUDF();
 			default:
 				throw new DMLRuntimeException("Unsupported encoder type: " + etype);
 		}
diff --git a/src/test/java/org/apache/sysds/test/functions/transform/TransformEncodeUDFTest.java b/src/test/java/org/apache/sysds/test/functions/transform/TransformEncodeUDFTest.java
index 1586a51b7d3..44ebcb81739 100644
--- a/src/test/java/org/apache/sysds/test/functions/transform/TransformEncodeUDFTest.java
+++ b/src/test/java/org/apache/sysds/test/functions/transform/TransformEncodeUDFTest.java
@@ -6,9 +6,9 @@
  * 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
@@ -29,28 +29,29 @@
 import org.apache.sysds.test.TestUtils;
 import org.apache.sysds.utils.Statistics;
 
-public class TransformEncodeUDFTest extends AutomatedTestBase 
-{
-	private final static String TEST_NAME1 = "TransformEncodeUDF1"; //min-max
-	private final static String TEST_NAME2 = "TransformEncodeUDF2"; //scale w/ defaults
+public class TransformEncodeUDFTest extends AutomatedTestBase {
+	private final static String TEST_NAME1 = "TransformEncodeUDF1"; // min-max
+	private final static String TEST_NAME2 = "TransformEncodeUDF2"; // scale w/ defaults
+	private final static String TEST_NAME3 = "TransformEncodeUDF3"; // simple custom UDF
 	private final static String TEST_DIR = "functions/transform/";
 	private final static String TEST_CLASS_DIR = TEST_DIR + TransformEncodeUDFTest.class.getSimpleName() + "/";
-	
-	//dataset and transform tasks without missing values
+
+	// dataset and transform tasks without missing values
 	private final static String DATASET = "homes3/homes.csv";
-	
+
 	@Override
-	public void setUp()  {
+	public void setUp() {
 		TestUtils.clearAssertionInformation();
-		addTestConfiguration(TEST_NAME1, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME1, new String[] {"R"}) );
-		addTestConfiguration(TEST_NAME2, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME2, new String[] {"R"}) );
+		addTestConfiguration(TEST_NAME1, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME1, new String[] {"R"}));
+		addTestConfiguration(TEST_NAME2, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME2, new String[] {"R"}));
+		addTestConfiguration(TEST_NAME3, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME3, new String[] {"R"}));
 	}
-	
+
 	@Test
 	public void testUDF1Singlenode() {
 		runTransformTest(ExecMode.SINGLE_NODE, TEST_NAME1);
 	}
-	
+
 	@Test
 	public void testUDF1Hybrid() {
 		runTransformTest(ExecMode.HYBRID, TEST_NAME1);
@@ -63,30 +64,37 @@ public void testUDF2Singlenode() {
 
 	@Test
 	public void testUDF2Hybrid() {
-	runTransformTest(ExecMode.HYBRID, TEST_NAME2);
+		runTransformTest(ExecMode.HYBRID, TEST_NAME2);
 	}
-	
-	private void runTransformTest(ExecMode rt, String testname)
-	{
-		//set runtime platform
+
+	@Test
+	public void testUDF3Singlenode() {
+		runTransformTest(ExecMode.SINGLE_NODE, TEST_NAME3);
+	}
+
+	@Test
+	public void testUDF3Hybrid() {
+		runTransformTest(ExecMode.HYBRID, TEST_NAME3);
+	}
+
+	private void runTransformTest(ExecMode rt, String testname) {
+		// set runtime platform
 		ExecMode rtold = setExecMode(rt);
-		
-		try
-		{
+
+		try {
 			getAndLoadTestConfiguration(testname);
-			
+
 			String HOME = SCRIPT_DIR + TEST_DIR;
 			fullDMLScriptName = HOME + testname + ".dml";
-			programArgs = new String[]{"-explain",
-				"-nvargs", "DATA=" + DATASET_DIR + DATASET, "R="+output("R")};
+			programArgs = new String[] {"-explain", "-nvargs", "DATA=" + DATASET_DIR + DATASET, "R=" + output("R")};
+
+			// compare transformencode+scale vs transformencode w/ UDF
+			runTest(true, false, null, -1);
 
-			//compare transformencode+scale vs transformencode w/ UDF
-			runTest(true, false, null, -1); 
-			
 			double ret = HDFSTool.readDoubleFromHDFSFile(output("R"));
-			Assert.assertEquals(Double.valueOf(148*9), Double.valueOf(ret));
-			
-			if( rt == ExecMode.HYBRID ) {
+			Assert.assertEquals(Double.valueOf(148 * 9), Double.valueOf(ret));
+
+			if(rt == ExecMode.HYBRID) {
 				Long num = Long.valueOf(Statistics.getNoOfExecutedSPInst());
 				Assert.assertEquals("Wrong number of executed Spark instructions: " + num, Long.valueOf(0), num);
 			}
diff --git a/src/test/scripts/functions/transform/TransformEncodeUDF3.dml b/src/test/scripts/functions/transform/TransformEncodeUDF3.dml
new file mode 100644
index 00000000000..6f8ae6f47b7
--- /dev/null
+++ b/src/test/scripts/functions/transform/TransformEncodeUDF3.dml
@@ -0,0 +1,26 @@
+#-------------------------------------------------------------
+#
+# 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.
+#
+#-------------------------------------------------------------
+
+F1 = read($DATA, data_type="frame", format="csv");
+
+
+
+