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<section id="creating-arrow-objects">
<span id="arrow-create"></span><h1><a class="toc-backref" href="#id1" role="doc-backlink">Creating Arrow Objects</a><a class="headerlink" href="#creating-arrow-objects" title="Link to this heading"></a></h1>
<p>A vector is the basic unit in the Arrow Java library. Data types
describe the types of values; ValueVectors are sequences of typed
values. Vectors represent a one-dimensional sequence of values of
the same type. They are mutable containers.</p>
<p>Vectors implement the interface <a class="reference external" href="https://arrow.apache.org/docs/java/vector.html">ValueVector</a>. The Arrow libraries provide
implementations of vectors for various data types.</p>
<nav class="contents" id="contents">
<p class="topic-title">Contents</p>
<ul class="simple">
<li><p><a class="reference internal" href="#creating-arrow-objects" id="id1">Creating Arrow Objects</a></p>
<ul>
<li><p><a class="reference internal" href="#creating-vectors-arrays" id="id2">Creating Vectors (arrays)</a></p>
<ul>
<li><p><a class="reference internal" href="#array-of-int" id="id3">Array of Int</a></p></li>
<li><p><a class="reference internal" href="#array-of-varchar" id="id4">Array of Varchar</a></p></li>
<li><p><a class="reference internal" href="#dictionary-encoded-array-of-varchar" id="id5">Dictionary-Encoded Array of Varchar</a></p></li>
<li><p><a class="reference internal" href="#array-of-list" id="id6">Array of List</a></p></li>
</ul>
</li>
<li><p><a class="reference internal" href="#slicing" id="id7">Slicing</a></p>
<ul>
<li><p><a class="reference internal" href="#slicing-intvector" id="id8">Slicing IntVector</a></p></li>
</ul>
</li>
</ul>
</li>
</ul>
</nav>
<section id="creating-vectors-arrays">
<h2><a class="toc-backref" href="#id2" role="doc-backlink">Creating Vectors (arrays)</a><a class="headerlink" href="#creating-vectors-arrays" title="Link to this heading"></a></h2>
<section id="array-of-int">
<h3><a class="toc-backref" href="#id3" role="doc-backlink">Array of Int</a><a class="headerlink" href="#array-of-int" title="Link to this heading"></a></h3>
<div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.IntVector</span><span class="p">;</span>
<span class="k">try</span><span class="p">(</span>
<span class="w"> </span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span>
<span class="w"> </span><span class="n">IntVector</span><span class="w"> </span><span class="n">intVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">IntVector</span><span class="p">(</span><span class="s">&quot;intVector&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">)</span>
<span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span>
<span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">);</span>
<span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">);</span>
<span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">);</span>
<span class="w"> </span><span class="n">intVector</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">print</span><span class="p">(</span><span class="n">intVector</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>[1, 2, 3]
</pre></div>
</div>
</section>
<section id="array-of-varchar">
<h3><a class="toc-backref" href="#id4" role="doc-backlink">Array of Varchar</a><a class="headerlink" href="#array-of-varchar" title="Link to this heading"></a></h3>
<div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.VarCharVector</span><span class="p">;</span>
<span class="k">try</span><span class="p">(</span>
<span class="w"> </span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span>
<span class="w"> </span><span class="n">VarCharVector</span><span class="w"> </span><span class="n">varCharVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">VarCharVector</span><span class="p">(</span><span class="s">&quot;varCharVector&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span>
<span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">varCharVector</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span>
<span class="w"> </span><span class="n">varCharVector</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;one&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">());</span>
<span class="w"> </span><span class="n">varCharVector</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;two&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">());</span>
<span class="w"> </span><span class="n">varCharVector</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;three&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">());</span>
<span class="w"> </span><span class="n">varCharVector</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">print</span><span class="p">(</span><span class="n">varCharVector</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>[one, two, three]
</pre></div>
</div>
</section>
<section id="dictionary-encoded-array-of-varchar">
<h3><a class="toc-backref" href="#id5" role="doc-backlink">Dictionary-Encoded Array of Varchar</a><a class="headerlink" href="#dictionary-encoded-array-of-varchar" title="Link to this heading"></a></h3>
<p>In some scenarios <a class="reference external" href="https://arrow.apache.org/docs/format/Columnar.html#dictionary-encoded-layout">dictionary-encoding</a> a column is useful to save memory.</p>
<div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.FieldVector</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.VarCharVector</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.dictionary.Dictionary</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.dictionary.DictionaryEncoder</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.types.pojo.ArrowType</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.types.pojo.DictionaryEncoding</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">java.nio.charset.StandardCharsets</span><span class="p">;</span>
<span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">root</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span>
<span class="w"> </span><span class="n">VarCharVector</span><span class="w"> </span><span class="n">countries</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">VarCharVector</span><span class="p">(</span><span class="s">&quot;country-dict&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">root</span><span class="p">);</span>
<span class="w"> </span><span class="n">VarCharVector</span><span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">VarCharVector</span><span class="p">(</span><span class="s">&quot;app-use-country-dict&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">root</span><span class="p">)</span>
<span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="mi">10</span><span class="p">);</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Andorra&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Cuba&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Grecia&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Guinea&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Islandia&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Malta&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">6</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tailandia&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Uganda&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Yemen&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Zambia&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">countries</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">10</span><span class="p">);</span>
<span class="w"> </span><span class="n">Dictionary</span><span class="w"> </span><span class="n">countriesDictionary</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">Dictionary</span><span class="p">(</span><span class="n">countries</span><span class="p">,</span>
<span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">DictionaryEncoding</span><span class="p">(</span><span class="cm">/*id=*/</span><span class="mi">1L</span><span class="p">,</span><span class="w"> </span><span class="cm">/*ordered=*/</span><span class="kc">false</span><span class="p">,</span><span class="w"> </span><span class="cm">/*indexType=*/</span><span class="k">new</span><span class="w"> </span><span class="n">ArrowType</span><span class="p">.</span><span class="na">Int</span><span class="p">(</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="kc">true</span><span class="p">)));</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="s">&quot;Dictionary: &quot;</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">countriesDictionary</span><span class="p">);</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">allocateNew</span><span class="p">(</span><span class="mi">5</span><span class="p">);</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Andorra&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Guinea&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Islandia&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Malta&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">set</span><span class="p">(</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Uganda&quot;</span><span class="p">.</span><span class="na">getBytes</span><span class="p">(</span><span class="n">StandardCharsets</span><span class="p">.</span><span class="na">UTF_8</span><span class="p">));</span>
<span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">5</span><span class="p">);</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="s">&quot;Unencoded data: &quot;</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">appUserCountriesUnencoded</span><span class="p">);</span>
<span class="w"> </span><span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">FieldVector</span><span class="w"> </span><span class="n">appUserCountriesDictionaryEncoded</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">FieldVector</span><span class="p">)</span><span class="w"> </span><span class="n">DictionaryEncoder</span>
<span class="w"> </span><span class="p">.</span><span class="na">encode</span><span class="p">(</span><span class="n">appUserCountriesUnencoded</span><span class="p">,</span><span class="w"> </span><span class="n">countriesDictionary</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="s">&quot;Dictionary-encoded data: &quot;</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">appUserCountriesDictionaryEncoded</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>Dictionary: Dictionary DictionaryEncoding[id=1,ordered=false,indexType=Int(8, true)] [Andorra, Cuba, Grecia, Guinea, Islandia, Malta, Tailandia, Uganda, Yemen, Zambia]
Unencoded data: [Andorra, Guinea, Islandia, Malta, Uganda]
Dictionary-encoded data: [0, 3, 4, 5, 7]
</pre></div>
</div>
</section>
<section id="array-of-list">
<h3><a class="toc-backref" href="#id6" role="doc-backlink">Array of List</a><a class="headerlink" href="#array-of-list" title="Link to this heading"></a></h3>
<div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.complex.impl.UnionListWriter</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.complex.ListVector</span><span class="p">;</span>
<span class="k">try</span><span class="p">(</span>
<span class="w"> </span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span>
<span class="w"> </span><span class="n">ListVector</span><span class="w"> </span><span class="n">listVector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ListVector</span><span class="p">.</span><span class="na">empty</span><span class="p">(</span><span class="s">&quot;listVector&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">);</span>
<span class="w"> </span><span class="n">UnionListWriter</span><span class="w"> </span><span class="n">listWriter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">listVector</span><span class="p">.</span><span class="na">getWriter</span><span class="p">()</span>
<span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="kt">int</span><span class="o">[]</span><span class="w"> </span><span class="n">data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="kt">int</span><span class="o">[]</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">20</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p">,</span><span class="w"> </span><span class="mi">100</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p">,</span><span class="w"> </span><span class="mi">300</span><span class="p">,</span><span class="w"> </span><span class="mi">1000</span><span class="p">,</span><span class="w"> </span><span class="mi">2000</span><span class="p">,</span><span class="w"> </span><span class="mi">3000</span><span class="w"> </span><span class="p">};</span>
<span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">tmp_index</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span>
<span class="w"> </span><span class="k">for</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">listWriter</span><span class="p">.</span><span class="na">setPosition</span><span class="p">(</span><span class="n">i</span><span class="p">);</span>
<span class="w"> </span><span class="n">listWriter</span><span class="p">.</span><span class="na">startList</span><span class="p">();</span>
<span class="w"> </span><span class="k">for</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">j</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">j</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w"> </span><span class="n">j</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">listWriter</span><span class="p">.</span><span class="na">writeInt</span><span class="p">(</span><span class="n">data</span><span class="o">[</span><span class="n">tmp_index</span><span class="o">]</span><span class="p">);</span>
<span class="w"> </span><span class="n">tmp_index</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">tmp_index</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n">listWriter</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">3</span><span class="p">);</span>
<span class="w"> </span><span class="n">listWriter</span><span class="p">.</span><span class="na">endList</span><span class="p">();</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n">listVector</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">4</span><span class="p">);</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">print</span><span class="p">(</span><span class="n">listVector</span><span class="p">);</span>
<span class="p">}</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="p">(</span><span class="n">Exception</span><span class="w"> </span><span class="n">e</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">e</span><span class="p">.</span><span class="na">printStackTrace</span><span class="p">();</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>[[1,2,3], [10,20,30], [100,200,300], [1000,2000,3000]]
</pre></div>
</div>
</section>
</section>
<section id="slicing">
<h2><a class="toc-backref" href="#id7" role="doc-backlink">Slicing</a><a class="headerlink" href="#slicing" title="Link to this heading"></a></h2>
<p>Slicing provides a way of copying a range of rows between two vectors of the same type.</p>
<section id="slicing-intvector">
<h3><a class="toc-backref" href="#id8" role="doc-backlink">Slicing IntVector</a><a class="headerlink" href="#slicing-intvector" title="Link to this heading"></a></h3>
<p>In this example, we copy a portion of the input IntVector to a new IntVector.</p>
<div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.BufferAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.memory.RootAllocator</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.IntVector</span><span class="p">;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">org.apache.arrow.vector.util.TransferPair</span><span class="p">;</span>
<span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">BufferAllocator</span><span class="w"> </span><span class="n">allocator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">RootAllocator</span><span class="p">();</span>
<span class="w"> </span><span class="n">IntVector</span><span class="w"> </span><span class="n">vector</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">IntVector</span><span class="p">(</span><span class="s">&quot;intVector&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">allocator</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="mi">10</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">vector</span><span class="p">.</span><span class="na">setSafe</span><span class="p">(</span><span class="n">i</span><span class="p">,</span><span class="w"> </span><span class="n">i</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n">vector</span><span class="p">.</span><span class="na">setValueCount</span><span class="p">(</span><span class="mi">10</span><span class="p">);</span>
<span class="w"> </span><span class="n">TransferPair</span><span class="w"> </span><span class="n">tp</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">vector</span><span class="p">.</span><span class="na">getTransferPair</span><span class="p">(</span><span class="n">allocator</span><span class="p">);</span>
<span class="w"> </span><span class="n">tp</span><span class="p">.</span><span class="na">splitAndTransfer</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p">);</span>
<span class="w"> </span><span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">IntVector</span><span class="w"> </span><span class="n">sliced</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">IntVector</span><span class="p">)</span><span class="w"> </span><span class="n">tp</span><span class="p">.</span><span class="na">getTo</span><span class="p">())</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">println</span><span class="p">(</span><span class="n">sliced</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n">tp</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">vector</span><span class="p">.</span><span class="na">getTransferPair</span><span class="p">(</span><span class="n">allocator</span><span class="p">);</span>
<span class="w"> </span><span class="c1">// copy 6 elements from index 2</span>
<span class="w"> </span><span class="n">tp</span><span class="p">.</span><span class="na">splitAndTransfer</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p">);</span>
<span class="w"> </span><span class="k">try</span><span class="w"> </span><span class="p">(</span><span class="n">IntVector</span><span class="w"> </span><span class="n">sliced</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">IntVector</span><span class="p">)</span><span class="w"> </span><span class="n">tp</span><span class="p">.</span><span class="na">getTo</span><span class="p">())</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">System</span><span class="p">.</span><span class="na">out</span><span class="p">.</span><span class="na">print</span><span class="p">(</span><span class="n">sliced</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>[0, 1, 2, 3, 4]
[2, 3, 4, 5, 6, 7]
</pre></div>
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