lidavidm commented on code in PR #320:
URL: https://github.com/apache/arrow-cookbook/pull/320#discussion_r1308070401
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java/source/data.rst:
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@@ -23,6 +23,47 @@ Recipes related to compare, filtering or transforming data.
.. contents::
+Concatenate Value Vectors
+=========================
+
+In some cases, we need to concatenate two value vectors into one. To accomplish
+this, we can use `VectorAppender`_. The following code create two vectors
separately,
+and then appends the two vectors together.
+
+.. testcode::
+
+ import org.apache.arrow.memory.BufferAllocator;
+ import org.apache.arrow.memory.RootAllocator;
+ import org.apache.arrow.vector.IntVector;
+ import org.apache.arrow.vector.ValueVector;
+ import org.apache.arrow.vector.util.VectorAppender;
+
+ try (
+ BufferAllocator allocator = new RootAllocator();
+ IntVector initialValues = new IntVector("initialValues", allocator);
+ IntVector toAppend = new IntVector("toAppend", allocator);
+ ) {
+ initialValues.allocateNew(2);
+ initialValues.set(0, 1);
+ initialValues.set(1, 2);
+ initialValues.setValueCount(2);
+ System.out.println("Initial IntVector: " + initialValues);
+ toAppend.allocateNew(4);
+ toAppend.set(1, 4);
+ toAppend.set(3, 6);
+ toAppend.setValueCount(4);
+ System.out.println("IntVector to Append: " + toAppend);
+ VectorAppender appenderUtil = new VectorAppender(initialValues);
+ ValueVector resultOfVectorsAppended = toAppend.accept(appenderUtil,
null);
Review Comment:
We don't need to close this? If it mutates the original vector, we should
write it in a way that makes that clear
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