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<li><a class="reference internal" href="#">Text Processing Tools</a><ul>
<li><a class="reference internal" href="#string-module">string module</a></li>
<li><a class="reference internal" href="#text-input">Text Input</a></li>
<li><a class="reference internal" href="#text-output">Text Output</a></li>
<li><a class="reference internal" href="#comparing-values">Comparing Values</a></li>
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<div class="section" id="text-processing-tools">
<span id="article-text-processing"></span><h1>Text Processing Tools<a class="headerlink" href="#text-processing-tools" title="Permalink to this headline">¶</a></h1>
<p>The string class is the most obvious text processing tool available to Python programmers, but there are plenty of other tools in the standard library to make text manipulation simpler.</p>
<div class="section" id="string-module">
<h2>string module<a class="headerlink" href="#string-module" title="Permalink to this headline">¶</a></h2>
<p>Old-style code will use functions from the <a class="reference internal" href="../string/index.html#module-string" title="string: Contains constants and classes for working with text."><tt class="xref py py-mod docutils literal"><span class="pre">string</span></tt></a> module, instead of methods of string objects. There is an equivalent method for each function from the module, and use of the functions is deprecated for new code.</p>
<p>Newer code may use a <tt class="docutils literal"><span class="pre">string.Template</span></tt> as a simple way to parameterize strings beyond the features of the string or unicode classes. While not as feature-rich as templates defined by many of the web frameworks or extension modules available on PyPI, <tt class="docutils literal"><span class="pre">string.Template</span></tt> is a good middle ground for user-modifiable templates where dynamic values need to be inserted into otherwise static text.</p>
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<h2>Text Input<a class="headerlink" href="#text-input" title="Permalink to this headline">¶</a></h2>
<p>Reading from a file is easy enough, but if you’re writing a line-by-line filter the <a class="reference internal" href="../fileinput/index.html#module-fileinput" title="fileinput: Process lines from input streams."><tt class="xref py py-mod docutils literal"><span class="pre">fileinput</span></tt></a> module is even easier. The fileinput API calls for you to iterate over the <tt class="docutils literal"><span class="pre">input()</span></tt> generator, processing each line as it is yielded. The generator handles parsing command line arguments for file names, or falling back to reading directly from <tt class="docutils literal"><span class="pre">sys.stdin</span></tt>. The result is a flexible tool your users can run directly on a file or as part of a pipeline.</p>
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<h2>Text Output<a class="headerlink" href="#text-output" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference internal" href="../textwrap/index.html#module-textwrap" title="textwrap: Formatting text by adjusting where line breaks occur in a paragraph."><tt class="xref py py-mod docutils literal"><span class="pre">textwrap</span></tt></a> module includes tools for formatting text from paragraphs by limiting the width of output, adding indentation, and inserting line breaks to wrap lines consistently.</p>
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<div class="section" id="comparing-values">
<h2>Comparing Values<a class="headerlink" href="#comparing-values" title="Permalink to this headline">¶</a></h2>
<p>The standard library includes two modules related to comparing text values beyond the built-in equality and sort comparison supported by string objects. <a class="reference internal" href="../re/index.html#module-re" title="re: Searching within and changing text using formal patterns."><tt class="xref py py-mod docutils literal"><span class="pre">re</span></tt></a> provides a complete regular expression library, implemented largely in C for performance. Regular expressions are well-suited for finding substrings within a larger data set, comparing strings against a pattern (rather than another fixed string), and mild parsing.</p>
<p><a class="reference internal" href="../difflib/index.html#module-difflib" title="difflib: Compare sequences, especially lines of text."><tt class="xref py py-mod docutils literal"><span class="pre">difflib</span></tt></a>, on the other hand, shows you the actual differences between sequences of text in terms of the parts added, removed, or changed. The output of the comparison functions in <a class="reference internal" href="../difflib/index.html#module-difflib" title="difflib: Compare sequences, especially lines of text."><tt class="xref py py-mod docutils literal"><span class="pre">difflib</span></tt></a> can be used to provide more detailed feedback to user about where changes occur in two inputs, how a document has changed over time, etc.</p>
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