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author | Andy Konwinski <andrew@apache.org> | 2013-08-23 17:44:20 +0000 |
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committer | Andy Konwinski <andrew@apache.org> | 2013-08-23 17:44:20 +0000 |
commit | 9a551ef906b9de00416b35b03253ff970557c25a (patch) | |
tree | 219b236eacfe9cb6ccb9afb021f3a2b1671b2723 /site/docs/0.7.3/python-programming-guide.html | |
parent | 57c18920c3eddd8bc94cd05419e11d652e67d9c3 (diff) | |
download | spark-website-9a551ef906b9de00416b35b03253ff970557c25a.tar.gz spark-website-9a551ef906b9de00416b35b03253ff970557c25a.tar.bz2 spark-website-9a551ef906b9de00416b35b03253ff970557c25a.zip |
add docs dir.
Diffstat (limited to 'site/docs/0.7.3/python-programming-guide.html')
-rw-r--r-- | site/docs/0.7.3/python-programming-guide.html | 271 |
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diff --git a/site/docs/0.7.3/python-programming-guide.html b/site/docs/0.7.3/python-programming-guide.html new file mode 100644 index 000000000..47fd8a45c --- /dev/null +++ b/site/docs/0.7.3/python-programming-guide.html @@ -0,0 +1,271 @@ +<!DOCTYPE html> +<!--[if lt IE 7]> <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]--> +<!--[if IE 7]> <html class="no-js lt-ie9 lt-ie8"> <![endif]--> +<!--[if IE 8]> <html class="no-js lt-ie9"> <![endif]--> +<!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]--> + <head> + <meta charset="utf-8"> + <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> + <title>Python Programming Guide - Spark 0.7.3 Documentation</title> + <meta name="description" content=""> + + <link rel="stylesheet" href="css/bootstrap.min.css"> + <style> + body { + padding-top: 60px; + padding-bottom: 40px; + } + </style> + <meta name="viewport" content="width=device-width"> + <link rel="stylesheet" href="css/bootstrap-responsive.min.css"> + <link rel="stylesheet" href="css/main.css"> + + <script src="js/vendor/modernizr-2.6.1-respond-1.1.0.min.js"></script> + + <link rel="stylesheet" href="css/pygments-default.css"> + + <!-- Google analytics script --> + <script type="text/javascript"> + var _gaq = _gaq || []; + _gaq.push(['_setAccount', 'UA-32518208-1']); + _gaq.push(['_trackPageview']); + + (function() { + var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; + ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; + var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); + })(); + </script> + + </head> + <body> + <!--[if lt IE 7]> + <p class="chromeframe">You are using an outdated browser. <a href="http://browsehappy.com/">Upgrade your browser today</a> or <a href="http://www.google.com/chromeframe/?redirect=true">install Google Chrome Frame</a> to better experience this site.</p> + <![endif]--> + + <!-- This code is taken from http://twitter.github.com/bootstrap/examples/hero.html --> + + <div class="navbar navbar-fixed-top" id="topbar"> + <div class="navbar-inner"> + <div class="container"> + <div class="brand"><a href="index.html"> + <img src="img/spark-logo-77x50px-hd.png" /></a><span class="version">0.7.3</span> + </div> + <ul class="nav"> + <!--TODO(andyk): Add class="active" attribute to li some how.--> + <li><a href="index.html">Overview</a></li> + + <li class="dropdown"> + <a href="#" class="dropdown-toggle" data-toggle="dropdown">Programming Guides<b class="caret"></b></a> + <ul class="dropdown-menu"> + <li><a href="quick-start.html">Quick Start</a></li> + <li><a href="scala-programming-guide.html">Scala</a></li> + <li><a href="java-programming-guide.html">Java</a></li> + <li><a href="python-programming-guide.html">Python</a></li> + <li><a href="streaming-programming-guide.html">Spark Streaming</a></li> + </ul> + </li> + + <li class="dropdown"> + <a href="#" class="dropdown-toggle" data-toggle="dropdown">API Docs<b class="caret"></b></a> + <ul class="dropdown-menu"> + <li><a href="api/core/index.html">Spark Java/Scala (Scaladoc)</a></li> + <li><a href="api/pyspark/index.html">Spark Python (Epydoc)</a></li> + <li><a href="api/streaming/index.html">Spark Streaming Java/Scala (Scaladoc) </a></li> + </ul> + </li> + + <li class="dropdown"> + <a href="#" class="dropdown-toggle" data-toggle="dropdown">Deploying<b class="caret"></b></a> + <ul class="dropdown-menu"> + <li><a href="ec2-scripts.html">Amazon EC2</a></li> + <li><a href="spark-standalone.html">Standalone Mode</a></li> + <li><a href="running-on-mesos.html">Mesos</a></li> + <li><a href="running-on-yarn.html">YARN</a></li> + </ul> + </li> + + <li class="dropdown"> + <a href="api.html" class="dropdown-toggle" data-toggle="dropdown">More<b class="caret"></b></a> + <ul class="dropdown-menu"> + <li><a href="building-with-maven.html">Building Spark with Maven</a></li> + <li><a href="configuration.html">Configuration</a></li> + <li><a href="tuning.html">Tuning Guide</a></li> + <li><a href="bagel-programming-guide.html">Bagel (Pregel on Spark)</a></li> + <li><a href="contributing-to-spark.html">Contributing to Spark</a></li> + </ul> + </li> + </ul> + <!--<p class="navbar-text pull-right"><span class="version-text">v0.7.3</span></p>--> + </div> + </div> + </div> + + <div class="container" id="content"> + <h1 class="title">Python Programming Guide</h1> + + <p>The Spark Python API (PySpark) exposes most of the Spark features available in the Scala version to Python. +To learn the basics of Spark, we recommend reading through the +<a href="scala-programming-guide.html">Scala programming guide</a> first; it should be +easy to follow even if you don’t know Scala. +This guide will show how to use the Spark features described there in Python.</p> + +<h1 id="key-differences-in-the-python-api">Key Differences in the Python API</h1> + +<p>There are a few key differences between the Python and Scala APIs:</p> + +<ul> + <li>Python is dynamically typed, so RDDs can hold objects of different types.</li> + <li>PySpark does not currently support the following Spark features: + <ul> + <li>Special functions on RDDs of doubles, such as <code>mean</code> and <code>stdev</code></li> + <li><code>lookup</code>, <code>sample</code> and <code>sort</code></li> + <li><code>persist</code> at storage levels other than <code>MEMORY_ONLY</code></li> + <li>Execution on Windows – this is slated for a future release</li> + </ul> + </li> +</ul> + +<p>In PySpark, RDDs support the same methods as their Scala counterparts but take Python functions and return Python collection types. +Short functions can be passed to RDD methods using Python’s <a href="http://www.diveintopython.net/power_of_introspection/lambda_functions.html"><code>lambda</code></a> syntax:</p> + +<div class="highlight"><pre><code class="python"><span class="n">logData</span> <span class="o">=</span> <span class="n">sc</span><span class="o">.</span><span class="n">textFile</span><span class="p">(</span><span class="n">logFile</span><span class="p">)</span><span class="o">.</span><span class="n">cache</span><span class="p">()</span> +<span class="n">errors</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="k">lambda</span> <span class="n">line</span><span class="p">:</span> <span class="s">"ERROR"</span> <span class="ow">in</span> <span class="n">line</span><span class="p">)</span> +</code></pre></div> + +<p>You can also pass functions that are defined using the <code>def</code> keyword; this is useful for more complicated functions that cannot be expressed using <code>lambda</code>:</p> + +<div class="highlight"><pre><code class="python"><span class="k">def</span> <span class="nf">is_error</span><span class="p">(</span><span class="n">line</span><span class="p">):</span> + <span class="k">return</span> <span class="s">"ERROR"</span> <span class="ow">in</span> <span class="n">line</span> +<span class="n">errors</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">is_error</span><span class="p">)</span> +</code></pre></div> + +<p>Functions can access objects in enclosing scopes, although modifications to those objects within RDD methods will not be propagated to other tasks:</p> + +<div class="highlight"><pre><code class="python"><span class="n">error_keywords</span> <span class="o">=</span> <span class="p">[</span><span class="s">"Exception"</span><span class="p">,</span> <span class="s">"Error"</span><span class="p">]</span> +<span class="k">def</span> <span class="nf">is_error</span><span class="p">(</span><span class="n">line</span><span class="p">):</span> + <span class="k">return</span> <span class="nb">any</span><span class="p">(</span><span class="n">keyword</span> <span class="ow">in</span> <span class="n">line</span> <span class="k">for</span> <span class="n">keyword</span> <span class="ow">in</span> <span class="n">error_keywords</span><span class="p">)</span> +<span class="n">errors</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">is_error</span><span class="p">)</span> +</code></pre></div> + +<p>PySpark will automatically ship these functions to workers, along with any objects that they reference. +Instances of classes will be serialized and shipped to workers by PySpark, but classes themselves cannot be automatically distributed to workers. +The <a href="#standalone-use">Standalone Use</a> section describes how to ship code dependencies to workers.</p> + +<h1 id="installing-and-configuring-pyspark">Installing and Configuring PySpark</h1> + +<p>PySpark requires Python 2.6 or higher. +PySpark jobs are executed using a standard cPython interpreter in order to support Python modules that use C extensions. +We have not tested PySpark with Python 3 or with alternative Python interpreters, such as <a href="http://pypy.org/">PyPy</a> or <a href="http://www.jython.org/">Jython</a>. +By default, PySpark’s scripts will run programs using <code>python</code>; an alternate Python executable may be specified by setting the <code>PYSPARK_PYTHON</code> environment variable in <code>conf/spark-env.sh</code>.</p> + +<p>All of PySpark’s library dependencies, including <a href="http://py4j.sourceforge.net/">Py4J</a>, are bundled with PySpark and automatically imported.</p> + +<p>Standalone PySpark jobs should be run using the <code>pyspark</code> script, which automatically configures the Java and Python environment using the settings in <code>conf/spark-env.sh</code>. +The script automatically adds the <code>pyspark</code> package to the <code>PYTHONPATH</code>.</p> + +<h1 id="interactive-use">Interactive Use</h1> + +<p>The <code>pyspark</code> script launches a Python interpreter that is configured to run PySpark jobs. To use <code>pyspark</code> interactively, first build Spark, then launch it directly from the command line without any options:</p> + +<div class="highlight"><pre><code class="bash"><span class="nv">$ </span>sbt/sbt package +<span class="nv">$ </span>./pyspark +</code></pre></div> + +<p>The Python shell can be used explore data interactively and is a simple way to learn the API:</p> + +<div class="highlight"><pre><code class="python"><span class="o">>>></span> <span class="n">words</span> <span class="o">=</span> <span class="n">sc</span><span class="o">.</span><span class="n">textFile</span><span class="p">(</span><span class="s">"/usr/share/dict/words"</span><span class="p">)</span> +<span class="o">>>></span> <span class="n">words</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="k">lambda</span> <span class="n">w</span><span class="p">:</span> <span class="n">w</span><span class="o">.</span><span class="n">startswith</span><span class="p">(</span><span class="s">"spar"</span><span class="p">))</span><span class="o">.</span><span class="n">take</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span> +<span class="p">[</span><span class="s">u'spar'</span><span class="p">,</span> <span class="s">u'sparable'</span><span class="p">,</span> <span class="s">u'sparada'</span><span class="p">,</span> <span class="s">u'sparadrap'</span><span class="p">,</span> <span class="s">u'sparagrass'</span><span class="p">]</span> +<span class="o">>>></span> <span class="n">help</span><span class="p">(</span><span class="n">pyspark</span><span class="p">)</span> <span class="c"># Show all pyspark functions</span> +</code></pre></div> + +<p>By default, the <code>pyspark</code> shell creates SparkContext that runs jobs locally. +To connect to a non-local cluster, set the <code>MASTER</code> environment variable. +For example, to use the <code>pyspark</code> shell with a <a href="spark-standalone.html">standalone Spark cluster</a>:</p> + +<div class="highlight"><pre><code class="bash"><span class="nv">$ MASTER</span><span class="o">=</span>spark://IP:PORT ./pyspark +</code></pre></div> + +<h1 id="standalone-use">Standalone Use</h1> + +<p>PySpark can also be used from standalone Python scripts by creating a SparkContext in your script and running the script using <code>pyspark</code>. +The Quick Start guide includes a <a href="quick-start.html#a-standalone-job-in-python">complete example</a> of a standalone Python job.</p> + +<p>Code dependencies can be deployed by listing them in the <code>pyFiles</code> option in the SparkContext constructor:</p> + +<div class="highlight"><pre><code class="python"><span class="kn">from</span> <span class="nn">pyspark</span> <span class="kn">import</span> <span class="n">SparkContext</span> +<span class="n">sc</span> <span class="o">=</span> <span class="n">SparkContext</span><span class="p">(</span><span class="s">"local"</span><span class="p">,</span> <span class="s">"Job Name"</span><span class="p">,</span> <span class="n">pyFiles</span><span class="o">=</span><span class="p">[</span><span class="s">'MyFile.py'</span><span class="p">,</span> <span class="s">'lib.zip'</span><span class="p">,</span> <span class="s">'app.egg'</span><span class="p">])</span> +</code></pre></div> + +<p>Files listed here will be added to the <code>PYTHONPATH</code> and shipped to remote worker machines. +Code dependencies can be added to an existing SparkContext using its <code>addPyFile()</code> method.</p> + +<h1 id="where-to-go-from-here">Where to Go from Here</h1> + +<p>PySpark includes several sample programs in the <a href="https://github.com/mesos/spark/tree/master/python/examples"><code>python/examples</code> folder</a>. +You can run them by passing the files to the <code>pyspark</code> script – for example <code>./pyspark python/examples/wordcount.py</code>. +Each program prints usage help when run without arguments.</p> + +<p>We currently provide <a href="api/pyspark/index.html">API documentation</a> for the Python API as Epydoc. +Many of the RDD method descriptions contain <a href="http://docs.python.org/2/library/doctest.html">doctests</a> that provide additional usage examples.</p> + + <!-- Main hero unit for a primary marketing message or call to action --> + <!--<div class="hero-unit"> + <h1>Hello, world!</h1> + <p>This is a template for a simple marketing or informational website. 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