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| <div class="section" id="pyarrow-dataset-scanner"> |
| <h1>pyarrow.dataset.Scanner<a class="headerlink" href="#pyarrow-dataset-scanner" title="Permalink to this headline">¶</a></h1> |
| <dl class="py class"> |
| <dt id="pyarrow.dataset.Scanner"> |
| <em class="property">class </em><code class="sig-prename descclassname">pyarrow.dataset.</code><code class="sig-name descname">Scanner</code><a class="headerlink" href="#pyarrow.dataset.Scanner" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Bases: <code class="xref py py-class docutils literal notranslate"><span class="pre">pyarrow.lib._Weakrefable</span></code></p> |
| <p>A materialized scan operation with context and options bound.</p> |
| <p>A scanner is the class that glues the scan tasks, data fragments and data |
| sources together.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>dataset</strong> (<a class="reference internal" href="pyarrow.dataset.Dataset.html#pyarrow.dataset.Dataset" title="pyarrow.dataset.Dataset"><em>Dataset</em></a>) – Dataset to scan.</p></li> |
| <li><p><strong>columns</strong> (<em>list of str</em><em>, </em><em>default None</em>) – List of columns to project. Order and duplicates will be preserved. |
| The columns will be passed down to Datasets and corresponding data |
| fragments to avoid loading, copying, and deserializing columns |
| that will not be required further down the compute chain. |
| By default all of the available columns are projected. Raises |
| an exception if any of the referenced column names does not exist |
| in the dataset’s Schema.</p></li> |
| <li><p><strong>filter</strong> (<a class="reference internal" href="pyarrow.dataset.Expression.html#pyarrow.dataset.Expression" title="pyarrow.dataset.Expression"><em>Expression</em></a><em>, </em><em>default None</em>) – Scan will return only the rows matching the filter. |
| If possible the predicate will be pushed down to exploit the |
| partition information or internal metadata found in the data |
| source, e.g. Parquet statistics. Otherwise filters the loaded |
| RecordBatches before yielding them.</p></li> |
| <li><p><strong>batch_size</strong> (<em>int</em><em>, </em><em>default 1M</em>) – The maximum row count for scanned record batches. If scanned |
| record batches are overflowing memory then this method can be |
| called to reduce their size.</p></li> |
| <li><p><strong>use_threads</strong> (<em>bool</em><em>, </em><em>default True</em>) – If enabled, then maximum parallelism will be used determined by |
| the number of available CPU cores.</p></li> |
| <li><p><strong>memory_pool</strong> (<a class="reference internal" href="pyarrow.MemoryPool.html#pyarrow.MemoryPool" title="pyarrow.MemoryPool"><em>MemoryPool</em></a><em>, </em><em>default None</em>) – For memory allocations, if required. If not specified, uses the |
| default pool.</p></li> |
| </ul> |
| </dd> |
| </dl> |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.__init__"> |
| <code class="sig-name descname">__init__</code><span class="sig-paren">(</span><em class="sig-param"><span class="o">*</span><span class="n">args</span></em>, <em class="sig-param"><span class="o">**</span><span class="n">kwargs</span></em><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.__init__" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Initialize self. See help(type(self)) for accurate signature.</p> |
| </dd></dl> |
| |
| <p class="rubric">Methods</p> |
| <table class="longtable docutils align-default"> |
| <colgroup> |
| <col style="width: 10%" /> |
| <col style="width: 90%" /> |
| </colgroup> |
| <tbody> |
| <tr class="row-odd"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.__init__" title="pyarrow.dataset.Scanner.__init__"><code class="xref py py-obj docutils literal notranslate"><span class="pre">__init__</span></code></a>(*args, **kwargs)</p></td> |
| <td><p>Initialize self.</p></td> |
| </tr> |
| <tr class="row-even"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.from_dataset" title="pyarrow.dataset.Scanner.from_dataset"><code class="xref py py-obj docutils literal notranslate"><span class="pre">from_dataset</span></code></a></p></td> |
| <td><p></p></td> |
| </tr> |
| <tr class="row-odd"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.from_fragment" title="pyarrow.dataset.Scanner.from_fragment"><code class="xref py py-obj docutils literal notranslate"><span class="pre">from_fragment</span></code></a></p></td> |
| <td><p></p></td> |
| </tr> |
| <tr class="row-even"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.get_fragments" title="pyarrow.dataset.Scanner.get_fragments"><code class="xref py py-obj docutils literal notranslate"><span class="pre">get_fragments</span></code></a></p></td> |
| <td><p>Returns an iterator over the fragments in this scan.</p></td> |
| </tr> |
| <tr class="row-odd"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.scan" title="pyarrow.dataset.Scanner.scan"><code class="xref py py-obj docutils literal notranslate"><span class="pre">scan</span></code></a></p></td> |
| <td><p>Returns a stream of ScanTasks</p></td> |
| </tr> |
| <tr class="row-even"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.to_batches" title="pyarrow.dataset.Scanner.to_batches"><code class="xref py py-obj docutils literal notranslate"><span class="pre">to_batches</span></code></a></p></td> |
| <td><p>Consume a Scanner in record batches.</p></td> |
| </tr> |
| <tr class="row-odd"><td><p><a class="reference internal" href="#pyarrow.dataset.Scanner.to_table" title="pyarrow.dataset.Scanner.to_table"><code class="xref py py-obj docutils literal notranslate"><span class="pre">to_table</span></code></a></p></td> |
| <td><p>Convert a Scanner into a Table.</p></td> |
| </tr> |
| </tbody> |
| </table> |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.from_dataset"> |
| <em class="property">static </em><code class="sig-name descname">from_dataset</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.from_dataset" title="Permalink to this definition">¶</a></dt> |
| <dd></dd></dl> |
| |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.from_fragment"> |
| <em class="property">static </em><code class="sig-name descname">from_fragment</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.from_fragment" title="Permalink to this definition">¶</a></dt> |
| <dd></dd></dl> |
| |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.get_fragments"> |
| <code class="sig-name descname">get_fragments</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.get_fragments" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Returns an iterator over the fragments in this scan.</p> |
| </dd></dl> |
| |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.scan"> |
| <code class="sig-name descname">scan</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.scan" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Returns a stream of ScanTasks</p> |
| <p>The caller is responsible to dispatch/schedule said tasks. Tasks should |
| be safe to run in a concurrent fashion and outlive the iterator.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Returns</dt> |
| <dd class="field-odd"><p><strong>scan_tasks</strong> (<em>iterator of ScanTask</em>)</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.to_batches"> |
| <code class="sig-name descname">to_batches</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.to_batches" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Consume a Scanner in record batches.</p> |
| <p>Sequentially executes the ScanTasks as the returned generator gets |
| consumed.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Returns</dt> |
| <dd class="field-odd"><p><strong>record_batches</strong> (<em>iterator of RecordBatch</em>)</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="py method"> |
| <dt id="pyarrow.dataset.Scanner.to_table"> |
| <code class="sig-name descname">to_table</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pyarrow.dataset.Scanner.to_table" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Convert a Scanner into a Table.</p> |
| <p>Use this convenience utility with care. This will serially materialize |
| the Scan result in memory before creating the Table.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Returns</dt> |
| <dd class="field-odd"><p><strong>table</strong> (<em>Table</em>)</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| </dd></dl> |
| |
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