SEARCH-11566: Add transpose Stream Evaluator to support transposing of matrices

solr/core/src/java/org/apache/solr/handler/StreamHandler.java

@@ -269,6 +269,7 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
         .withFunctionName("harmonicFit", HarmonicFitEvaluator.class)
         .withFunctionName("loess", LoessEvaluator.class)
         .withFunctionName("matrix", MatrixEvaluator.class)
+        .withFunctionName("transpose", TransposeEvaluator.class)
 
         // Boolean Stream Evaluators
 

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/FieldValueEvaluator.java

@@ -70,6 +70,8 @@ public class FieldValueEvaluator extends SourceEvaluator {
           list.add(obj);
         }
         return list;
+      } else if(value instanceof Matrix) {
+        return value;
       }
       else if(value instanceof Iterable && !(value instanceof List<?>)){
         Iterable<?> iter = (Iterable<?>)value;

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/Matrix.java

@@ -29,6 +29,10 @@ public class Matrix implements Iterable {
     this.data = data;
   }
 
+  public double[][] getData() {
+    return this.data;
+  }
+
   public Iterator iterator() {
     return new MatrixIterator(data);
   }

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/TransposeEvaluator.java

@@ -0,0 +1,52 @@
+/*
+ * 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.solr.client.solrj.io.eval;
+
+import java.io.IOException;
+
+import java.util.Locale;
+
+import org.apache.commons.math3.linear.Array2DRowRealMatrix;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class TransposeEvaluator extends RecursiveObjectEvaluator implements OneValueWorker {
+  protected static final long serialVersionUID = 1L;
+
+  public TransposeEvaluator(StreamExpression expression, StreamFactory factory) throws IOException{
+    super(expression, factory);
+
+    if(1 != containedEvaluators.size()){
+      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting exactly 1 value but found %d",expression,containedEvaluators.size()));
+    }
+  }
+
+  @Override
+  public Object doWork(Object value) throws IOException{
+    if(null == value){
+      return null;
+    } else if(value instanceof Matrix) {
+      Matrix matrix = (Matrix) value;
+      double[][] data = matrix.getData();
+      Array2DRowRealMatrix amatrix = new Array2DRowRealMatrix(data);
+      Array2DRowRealMatrix tmatrix = (Array2DRowRealMatrix)amatrix.transpose();
+      return new Matrix(tmatrix.getData());
+    } else {
+      throw new IOException("matrix parameter expected for transpose function");
+    }
+  }
+}

solr/solrj/src/test/org/apache/solr/client/solrj/io/stream/StreamExpressionTest.java

@@ -6065,6 +6065,38 @@ public class StreamExpressionTest extends SolrCloudTestCase {
     assertEquals(array2.get(2).doubleValue(), 4.0, 0.0);
   }
 
+
+  @Test
+  public void testTranspose() throws Exception {
+    String cexpr = "let(a=matrix(array(1,2,3), array(4,5,6)), b=transpose(a))";
+    ModifiableSolrParams paramsLoc = new ModifiableSolrParams();
+    paramsLoc.set("expr", cexpr);
+    paramsLoc.set("qt", "/stream");
+    String url = cluster.getJettySolrRunners().get(0).getBaseUrl().toString()+"/"+COLLECTIONORALIAS;
+    TupleStream solrStream = new SolrStream(url, paramsLoc);
+    StreamContext context = new StreamContext();
+    solrStream.setStreamContext(context);
+    List<Tuple> tuples = getTuples(solrStream);
+    assertTrue(tuples.size() == 1);
+    List<List<Number>> out = (List<List<Number>>)tuples.get(0).get("b");
+    assertEquals(out.size(), 3);
+    List<Number> array1 = out.get(0);
+    assertEquals(array1.size(), 2);
+    assertEquals(array1.get(0).doubleValue(), 1.0, 0.0);
+    assertEquals(array1.get(1).doubleValue(), 4.0, 0.0);
+
+    List<Number> array2 = out.get(1);
+    assertEquals(array2.size(), 2);
+    assertEquals(array2.get(0).doubleValue(), 2.0, 0.0);
+    assertEquals(array2.get(1).doubleValue(), 5.0, 0.0);
+
+    List<Number> array3 = out.get(2);
+    assertEquals(array3.size(), 2);
+    assertEquals(array3.get(0).doubleValue(), 3.0, 0.0);
+    assertEquals(array3.get(1).doubleValue(), 6.0, 0.0);
+  }
+
+
   @Test
   public void testAddAll() throws Exception {
     String cexpr = "addAll(array(1, 2, 3), array(4.5, 5.5, 6.5), array(7,8,9))";