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| <div class="section" id="module-apache_beam.transforms.util"> |
| <span id="apache-beam-transforms-util-module"></span><h1>apache_beam.transforms.util module<a class="headerlink" href="#module-apache_beam.transforms.util" title="Permalink to this headline">¶</a></h1> |
| <p>Simple utility PTransforms.</p> |
| <dl class="class"> |
| <dt id="apache_beam.transforms.util.CoGroupByKey"> |
| <em class="property">class </em><code class="descclassname">apache_beam.transforms.util.</code><code class="descname">CoGroupByKey</code><span class="sig-paren">(</span><em>**kwargs</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#CoGroupByKey"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.CoGroupByKey" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Bases: <a class="reference internal" href="apache_beam.transforms.ptransform.html#apache_beam.transforms.ptransform.PTransform" title="apache_beam.transforms.ptransform.PTransform"><code class="xref py py-class docutils literal"><span class="pre">apache_beam.transforms.ptransform.PTransform</span></code></a></p> |
| <p>Groups results across several PCollections by key.</p> |
| <p>Given an input dict of serializable keys (called “tags”) to 0 or more |
| PCollections of (key, value) tuples, it creates a single output PCollection |
| of (key, value) tuples whose keys are the unique input keys from all inputs, |
| and whose values are dicts mapping each tag to an iterable of whatever values |
| were under the key in the corresponding PCollection, in this manner:</p> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">(</span><span class="s1">'some key'</span><span class="p">,</span> <span class="p">{</span><span class="s1">'tag1'</span><span class="p">:</span> <span class="p">[</span><span class="s1">'value 1 under "some key" in pcoll1'</span><span class="p">,</span> |
| <span class="s1">'value 2 under "some key" in pcoll1'</span><span class="p">,</span> |
| <span class="o">...</span><span class="p">],</span> |
| <span class="s1">'tag2'</span><span class="p">:</span> <span class="o">...</span> <span class="p">,</span> |
| <span class="o">...</span> <span class="p">})</span> |
| </pre></div> |
| </div> |
| <p>For example, given:</p> |
| <blockquote> |
| <div>{‘tag1’: pc1, ‘tag2’: pc2, 333: pc3}</div></blockquote> |
| <dl class="docutils"> |
| <dt>where:</dt> |
| <dd>pc1 = [(k1, v1)] |
| pc2 = [] |
| pc3 = [(k1, v31), (k1, v32), (k2, v33)]</dd> |
| </dl> |
| <p>The output PCollection would be:</p> |
| <blockquote> |
| <div><dl class="docutils"> |
| <dt>[(k1, {‘tag1’: [v1], ‘tag2’: [], 333: [v31, v32]}),</dt> |
| <dd>(k2, {‘tag1’: [], ‘tag2’: [], 333: [v33]})]</dd> |
| </dl> |
| </div></blockquote> |
| <p>CoGroupByKey also works for tuples, lists, or other flat iterables of |
| PCollections, in which case the values of the resulting PCollections |
| will be tuples whose nth value is the list of values from the nth |
| PCollection—conceptually, the “tags” are the indices into the input. |
| Thus, for this input:</p> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">(</span><span class="n">pc1</span><span class="p">,</span> <span class="n">pc2</span><span class="p">,</span> <span class="n">pc3</span><span class="p">)</span> |
| </pre></div> |
| </div> |
| <p>the output would be:</p> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[(</span><span class="n">k1</span><span class="p">,</span> <span class="p">([</span><span class="n">v1</span><span class="p">],</span> <span class="p">[],</span> <span class="p">[</span><span class="n">v31</span><span class="p">,</span> <span class="n">v32</span><span class="p">]),</span> |
| <span class="p">(</span><span class="n">k2</span><span class="p">,</span> <span class="p">([],</span> <span class="p">[],</span> <span class="p">[</span><span class="n">v33</span><span class="p">]))]</span> |
| </pre></div> |
| </div> |
| <dl class="attribute"> |
| <dt> |
| <code class="descname">**kwargs</code></dt> |
| <dd><p>Accepts a single named argument “pipeline”, which specifies the |
| pipeline that “owns” this PTransform. Ordinarily CoGroupByKey can obtain |
| this information from one of the input PCollections, but if there are none |
| (or if there’s a chance there may be none), this argument is the only way |
| to provide pipeline information, and should be considered mandatory.</p> |
| </dd></dl> |
| |
| <dl class="method"> |
| <dt id="apache_beam.transforms.util.CoGroupByKey.expand"> |
| <code class="descname">expand</code><span class="sig-paren">(</span><em>pcolls</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#CoGroupByKey.expand"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.CoGroupByKey.expand" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Performs CoGroupByKey on argument pcolls; see class docstring.</p> |
| </dd></dl> |
| |
| </dd></dl> |
| |
| <dl class="function"> |
| <dt id="apache_beam.transforms.util.Keys"> |
| <code class="descclassname">apache_beam.transforms.util.</code><code class="descname">Keys</code><span class="sig-paren">(</span><em>label='Keys'</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#Keys"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.Keys" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Produces a PCollection of first elements of 2-tuples in a PCollection.</p> |
| </dd></dl> |
| |
| <dl class="function"> |
| <dt id="apache_beam.transforms.util.Values"> |
| <code class="descclassname">apache_beam.transforms.util.</code><code class="descname">Values</code><span class="sig-paren">(</span><em>label='Values'</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#Values"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.Values" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Produces a PCollection of second elements of 2-tuples in a PCollection.</p> |
| </dd></dl> |
| |
| <dl class="function"> |
| <dt id="apache_beam.transforms.util.KvSwap"> |
| <code class="descclassname">apache_beam.transforms.util.</code><code class="descname">KvSwap</code><span class="sig-paren">(</span><em>label='KvSwap'</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#KvSwap"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.KvSwap" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Produces a PCollection reversing 2-tuples in a PCollection.</p> |
| </dd></dl> |
| |
| <dl class="function"> |
| <dt id="apache_beam.transforms.util.RemoveDuplicates"> |
| <code class="descclassname">apache_beam.transforms.util.</code><code class="descname">RemoveDuplicates</code><span class="sig-paren">(</span><em>*args</em>, <em>**kwargs</em><span class="sig-paren">)</span><a class="headerlink" href="#apache_beam.transforms.util.RemoveDuplicates" title="Permalink to this definition">¶</a></dt> |
| <dd></dd></dl> |
| |
| <dl class="class"> |
| <dt id="apache_beam.transforms.util.BatchElements"> |
| <em class="property">class </em><code class="descclassname">apache_beam.transforms.util.</code><code class="descname">BatchElements</code><span class="sig-paren">(</span><em>min_batch_size=1</em>, <em>max_batch_size=10000</em>, <em>target_batch_overhead=0.05</em>, <em>target_batch_duration_secs=1</em>, <em>clock=<built-in function time></em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#BatchElements"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.BatchElements" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Bases: <a class="reference internal" href="apache_beam.transforms.ptransform.html#apache_beam.transforms.ptransform.PTransform" title="apache_beam.transforms.ptransform.PTransform"><code class="xref py py-class docutils literal"><span class="pre">apache_beam.transforms.ptransform.PTransform</span></code></a></p> |
| <p>A Transform that batches elements for amortized processing.</p> |
| <p>This transform is designed to precede operations whose processing cost |
| is of the form</p> |
| <blockquote> |
| <div>time = fixed_cost + num_elements * per_element_cost</div></blockquote> |
| <p>where the per element cost is (often significantly) smaller than the fixed |
| cost and could be amortized over multiple elements. It consumes a PCollection |
| of element type T and produces a PCollection of element type List[T].</p> |
| <p>This transform attempts to find the best batch size between the minimim |
| and maximum parameters by profiling the time taken by (fused) downstream |
| operations. For a fixed batch size, set the min and max to be equal.</p> |
| <p>Elements are batched per-window and batches emitted in the window |
| corresponding to its contents.</p> |
| <table class="docutils field-list" frame="void" rules="none"> |
| <col class="field-name" /> |
| <col class="field-body" /> |
| <tbody valign="top"> |
| <tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple"> |
| <li><strong>min_batch_size</strong> – (optional) the smallest number of elements per batch</li> |
| <li><strong>max_batch_size</strong> – (optional) the largest number of elements per batch</li> |
| <li><strong>target_batch_overhead</strong> – (optional) a target for fixed_cost / time, |
| as used in the formula above</li> |
| <li><strong>target_batch_duration_secs</strong> – (optional) a target for total time per bundle, |
| in seconds</li> |
| <li><strong>clock</strong> – (optional) an alternative to time.time for measuring the cost of |
| donwstream operations (mostly for testing)</li> |
| </ul> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <dl class="method"> |
| <dt id="apache_beam.transforms.util.BatchElements.expand"> |
| <code class="descname">expand</code><span class="sig-paren">(</span><em>pcoll</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#BatchElements.expand"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.BatchElements.expand" title="Permalink to this definition">¶</a></dt> |
| <dd></dd></dl> |
| |
| </dd></dl> |
| |
| <dl class="class"> |
| <dt id="apache_beam.transforms.util.Reshuffle"> |
| <em class="property">class </em><code class="descclassname">apache_beam.transforms.util.</code><code class="descname">Reshuffle</code><span class="sig-paren">(</span><em>label=None</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#Reshuffle"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.Reshuffle" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Bases: <a class="reference internal" href="apache_beam.transforms.ptransform.html#apache_beam.transforms.ptransform.PTransform" title="apache_beam.transforms.ptransform.PTransform"><code class="xref py py-class docutils literal"><span class="pre">apache_beam.transforms.ptransform.PTransform</span></code></a></p> |
| <p>PTransform that returns a PCollection equivalent to its input, |
| but operationally provides some of the side effects of a GroupByKey, |
| in particular preventing fusion of the surrounding transforms, |
| checkpointing, and deduplication by id.</p> |
| <p>Reshuffle adds a temporary random key to each element, performs a |
| ReshufflePerKey, and finally removes the temporary key.</p> |
| <p>Reshuffle is experimental. No backwards compatibility guarantees.</p> |
| <dl class="method"> |
| <dt id="apache_beam.transforms.util.Reshuffle.expand"> |
| <code class="descname">expand</code><span class="sig-paren">(</span><em>pcoll</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/apache_beam/transforms/util.html#Reshuffle.expand"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#apache_beam.transforms.util.Reshuffle.expand" title="Permalink to this definition">¶</a></dt> |
| <dd></dd></dl> |
| |
| </dd></dl> |
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