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| |
| <h1>ChunkedArray class</h1> |
| <small class="dont-index">Source: <a href="https://github.com/apache/arrow/blob/main/r/R/chunked-array.R" class="external-link"><code>R/chunked-array.R</code></a></small> |
| <div class="d-none name"><code>ChunkedArray-class.Rd</code></div> |
| </div> |
| |
| <div class="ref-description section level2"> |
| <p>A <code>ChunkedArray</code> is a data structure managing a list of |
| primitive Arrow <a href="array-class.html">Arrays</a> logically as one large array. Chunked arrays |
| may be grouped together in a <a href="Table-class.html">Table</a>.</p> |
| </div> |
| |
| |
| <div class="section level2"> |
| <h2 id="factory">Factory<a class="anchor" aria-label="anchor" href="#factory"></a></h2> |
| |
| |
| <p>The <code>ChunkedArray$create()</code> factory method instantiates the object from |
| various Arrays or R vectors. <code><a href="chunked_array.html">chunked_array()</a></code> is an alias for it.</p> |
| </div> |
| <div class="section level2"> |
| <h2 id="methods">Methods<a class="anchor" aria-label="anchor" href="#methods"></a></h2> |
| |
| |
| <ul><li><p><code>$length()</code>: Size in the number of elements this array contains</p></li> |
| <li><p><code>$chunk(i)</code>: Extract an <code>Array</code> chunk by integer position</p></li> |
| <li><p>`$nbytes() : Total number of bytes consumed by the elements of the array</p></li> |
| <li><p><code>$as_vector()</code>: convert to an R vector</p></li> |
| <li><p><code>$Slice(offset, length = NULL)</code>: Construct a zero-copy slice of the array |
| with the indicated offset and length. If length is <code>NULL</code>, the slice goes |
| until the end of the array.</p></li> |
| <li><p><code>$Take(i)</code>: return a <code>ChunkedArray</code> with values at positions given by |
| integers <code>i</code>. If <code>i</code> is an Arrow <code>Array</code> or <code>ChunkedArray</code>, it will be |
| coerced to an R vector before taking.</p></li> |
| <li><p><code>$Filter(i, keep_na = TRUE)</code>: return a <code>ChunkedArray</code> with values at positions where |
| logical vector or Arrow boolean-type <code>(Chunked)Array</code> <code>i</code> is <code>TRUE</code>.</p></li> |
| <li><p><code>$SortIndices(descending = FALSE)</code>: return an <code>Array</code> of integer positions that can be |
| used to rearrange the <code>ChunkedArray</code> in ascending or descending order</p></li> |
| <li><p><code>$cast(target_type, safe = TRUE, options = cast_options(safe))</code>: Alter the |
| data in the array to change its type.</p></li> |
| <li><p><code>$null_count</code>: The number of null entries in the array</p></li> |
| <li><p><code>$chunks</code>: return a list of <code>Array</code>s</p></li> |
| <li><p><code>$num_chunks</code>: integer number of chunks in the <code>ChunkedArray</code></p></li> |
| <li><p><code>$type</code>: logical type of data</p></li> |
| <li><p><code>$View(type)</code>: Construct a zero-copy view of this <code>ChunkedArray</code> with the |
| given type.</p></li> |
| <li><p><code>$Validate()</code>: Perform any validation checks to determine obvious inconsistencies |
| within the array's internal data. This can be an expensive check, potentially <code>O(length)</code></p></li> |
| </ul></div> |
| <div class="section level2"> |
| <h2 id="see-also">See also<a class="anchor" aria-label="anchor" href="#see-also"></a></h2> |
| <div class="dont-index"><p><a href="array-class.html">Array</a></p></div> |
| </div> |
| |
| <div class="section level2"> |
| <h2 id="ref-examples">Examples<a class="anchor" aria-label="anchor" href="#ref-examples"></a></h2> |
| <div class="sourceCode"><pre class="sourceCode r"><code><span class="r-in"><span><span class="co"># Pass items into chunked_array as separate objects to create chunks</span></span></span> |
| <span class="r-in"><span><span class="va">class_scores</span> <span class="op"><-</span> <span class="fu"><a href="chunked_array.html">chunked_array</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">87</span>, <span class="fl">88</span>, <span class="fl">89</span><span class="op">)</span>, <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">94</span>, <span class="fl">93</span>, <span class="fl">92</span><span class="op">)</span>, <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">71</span>, <span class="fl">72</span>, <span class="fl">73</span><span class="op">)</span><span class="op">)</span></span></span> |
| <span class="r-in"><span><span class="va">class_scores</span><span class="op">$</span><span class="va">num_chunks</span></span></span> |
| <span class="r-out co"><span class="r-pr">#></span> [1] 3</span> |
| <span class="r-in"><span></span></span> |
| <span class="r-in"><span><span class="co"># When taking a Slice from a chunked_array, chunks are preserved</span></span></span> |
| <span class="r-in"><span><span class="va">class_scores</span><span class="op">$</span><span class="fu">Slice</span><span class="op">(</span><span class="fl">2</span>, length <span class="op">=</span> <span class="fl">5</span><span class="op">)</span></span></span> |
| <span class="r-out co"><span class="r-pr">#></span> ChunkedArray</span> |
| <span class="r-out co"><span class="r-pr">#></span> <double></span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 89</span> |
| <span class="r-out co"><span class="r-pr">#></span> ],</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 94,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 93,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 92</span> |
| <span class="r-out co"><span class="r-pr">#></span> ],</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 71</span> |
| <span class="r-out co"><span class="r-pr">#></span> ]</span> |
| <span class="r-out co"><span class="r-pr">#></span> ]</span> |
| <span class="r-in"><span></span></span> |
| <span class="r-in"><span><span class="co"># You can combine Take and SortIndices to return a ChunkedArray with 1 chunk</span></span></span> |
| <span class="r-in"><span><span class="co"># containing all values, ordered.</span></span></span> |
| <span class="r-in"><span><span class="va">class_scores</span><span class="op">$</span><span class="fu">Take</span><span class="op">(</span><span class="va">class_scores</span><span class="op">$</span><span class="fu">SortIndices</span><span class="op">(</span>descending <span class="op">=</span> <span class="cn">TRUE</span><span class="op">)</span><span class="op">)</span></span></span> |
| <span class="r-out co"><span class="r-pr">#></span> ChunkedArray</span> |
| <span class="r-out co"><span class="r-pr">#></span> <double></span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 94,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 93,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 92,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 89,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 88,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 87,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 73,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 72,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 71</span> |
| <span class="r-out co"><span class="r-pr">#></span> ]</span> |
| <span class="r-out co"><span class="r-pr">#></span> ]</span> |
| <span class="r-in"><span></span></span> |
| <span class="r-in"><span><span class="co"># If you pass a list into chunked_array, you get a list of length 1</span></span></span> |
| <span class="r-in"><span><span class="va">list_scores</span> <span class="op"><-</span> <span class="fu"><a href="chunked_array.html">chunked_array</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/list.html" class="external-link">list</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">9.9</span>, <span class="fl">9.6</span>, <span class="fl">9.5</span><span class="op">)</span>, <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">8.2</span>, <span class="fl">8.3</span>, <span class="fl">8.4</span><span class="op">)</span>, <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">10.0</span>, <span class="fl">9.9</span>, <span class="fl">9.8</span><span class="op">)</span><span class="op">)</span><span class="op">)</span></span></span> |
| <span class="r-in"><span><span class="va">list_scores</span><span class="op">$</span><span class="va">num_chunks</span></span></span> |
| <span class="r-out co"><span class="r-pr">#></span> [1] 1</span> |
| <span class="r-in"><span></span></span> |
| <span class="r-in"><span><span class="co"># When constructing a ChunkedArray, the first chunk is used to infer type.</span></span></span> |
| <span class="r-in"><span><span class="va">doubles</span> <span class="op"><-</span> <span class="fu"><a href="chunked_array.html">chunked_array</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">1</span>, <span class="fl">2</span>, <span class="fl">3</span><span class="op">)</span>, <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">5L</span>, <span class="fl">6L</span>, <span class="fl">7L</span><span class="op">)</span><span class="op">)</span></span></span> |
| <span class="r-in"><span><span class="va">doubles</span><span class="op">$</span><span class="va">type</span></span></span> |
| <span class="r-out co"><span class="r-pr">#></span> Float64</span> |
| <span class="r-out co"><span class="r-pr">#></span> double</span> |
| <span class="r-in"><span></span></span> |
| <span class="r-in"><span><span class="co"># Concatenating chunked arrays returns a new chunked array containing all chunks</span></span></span> |
| <span class="r-in"><span><span class="va">a</span> <span class="op"><-</span> <span class="fu"><a href="chunked_array.html">chunked_array</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">1</span>, <span class="fl">2</span><span class="op">)</span>, <span class="fl">3</span><span class="op">)</span></span></span> |
| <span class="r-in"><span><span class="va">b</span> <span class="op"><-</span> <span class="fu"><a href="chunked_array.html">chunked_array</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">4</span>, <span class="fl">5</span><span class="op">)</span>, <span class="fl">6</span><span class="op">)</span></span></span> |
| <span class="r-in"><span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="va">a</span>, <span class="va">b</span><span class="op">)</span></span></span> |
| <span class="r-out co"><span class="r-pr">#></span> ChunkedArray</span> |
| <span class="r-out co"><span class="r-pr">#></span> <double></span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 1,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 2</span> |
| <span class="r-out co"><span class="r-pr">#></span> ],</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 3</span> |
| <span class="r-out co"><span class="r-pr">#></span> ],</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 4,</span> |
| <span class="r-out co"><span class="r-pr">#></span> 5</span> |
| <span class="r-out co"><span class="r-pr">#></span> ],</span> |
| <span class="r-out co"><span class="r-pr">#></span> [</span> |
| <span class="r-out co"><span class="r-pr">#></span> 6</span> |
| <span class="r-out co"><span class="r-pr">#></span> ]</span> |
| <span class="r-out co"><span class="r-pr">#></span> ]</span> |
| </code></pre></div> |
| </div> |
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