<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Miscellaneous Features — Astropy v0.2.4</title>
<link rel="stylesheet" href="../../../_static/bootstrap-astropy.css" type="text/css" />
<link rel="stylesheet" href="../../../_static/pygments.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../../../',
VERSION: '0.2.4',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="../../../_static/jquery.js"></script>
<script type="text/javascript" src="../../../_static/underscore.js"></script>
<script type="text/javascript" src="../../../_static/doctools.js"></script>
<script type="text/javascript" src="../../../_static/sidebar.js"></script>
<link rel="shortcut icon" href="../../../_static/astropy_logo.ico"/>
<link rel="top" title="Astropy v0.2.4" href="../../../index.html" />
<link rel="up" title="FITS File handling (astropy.io.fits)" href="../index.html" />
<link rel="next" title="Examples" href="examples.html" />
<link rel="prev" title="Executable Scripts" href="scripts.html" />
</head>
<body>
<div class="topbar">
<a class="brand" title="Documentation Home" href="../../../index.html"></a>
<ul>
<li><a class="homelink" title="AstroPy Homepage" href="http://www.astropy.org"></a></li>
<li><a title="General Index" href="../../../genindex.html">Index</a></li>
<li><a title="Python Module Index" href="../../../py-modindex.html">Modules</a></li>
<li>
<form action="../../../search.html" method="get">
<input type="text" name="q" placeholder="Search" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</li>
</ul>
</div>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right">
<a href="examples.html" title="Examples">
next »
</a>
</li>
<li class="right">
<a href="scripts.html" title="Executable Scripts">
« previous
</a>
|
</li>
<li>
<a href="../../../index.html">Astropy v0.2.4</a>
»
</li>
<li><a href="../index.html" accesskey="U">FITS File handling (<tt class="docutils literal"><span class="pre">astropy.io.fits</span></tt>)</a> »</li>
<li>Miscellaneous Features</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body">
<div class="section" id="miscellaneous-features">
<h1>Miscellaneous Features<a class="headerlink" href="#miscellaneous-features" title="Permalink to this headline">¶</a></h1>
<p>This section describes some of the miscellaneous features of <tt class="xref py py-obj docutils literal"><span class="pre">astropy.io.fits</span></tt>.</p>
<div class="section" id="differs">
<h2>Differs<a class="headerlink" href="#differs" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference internal" href="../api/diff.html#module-astropy.io.fits.diff" title="astropy.io.fits.diff"><tt class="xref py py-mod docutils literal"><span class="pre">astropy.io.fits.diff</span></tt></a> module contains several facilities for
generating and reporting the differences between two FITS files, or two
components of a FITS file.</p>
<p>The <a class="reference internal" href="../api/diff.html#astropy.io.fits.FITSDiff" title="astropy.io.fits.FITSDiff"><tt class="xref py py-class docutils literal"><span class="pre">FITSDiff</span></tt></a> class can be used to generate and represent the
differences between either two FITS files on disk, or two existing
<a class="reference internal" href="../api/hdulists.html#astropy.io.fits.HDUList" title="astropy.io.fits.HDUList"><tt class="xref py py-class docutils literal"><span class="pre">HDUList</span></tt></a> objects (or some combination thereof).</p>
<p>Likewise, the <a class="reference internal" href="../api/diff.html#astropy.io.fits.HeaderDiff" title="astropy.io.fits.HeaderDiff"><tt class="xref py py-class docutils literal"><span class="pre">HeaderDiff</span></tt></a> class can be used to find the differences
just between two <a class="reference internal" href="../api/headers.html#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-class docutils literal"><span class="pre">Header</span></tt></a> objects. Other available differs include
<a class="reference internal" href="../api/diff.html#astropy.io.fits.HDUDiff" title="astropy.io.fits.HDUDiff"><tt class="xref py py-class docutils literal"><span class="pre">HDUDiff</span></tt></a>, <a class="reference internal" href="../api/diff.html#astropy.io.fits.ImageDataDiff" title="astropy.io.fits.ImageDataDiff"><tt class="xref py py-class docutils literal"><span class="pre">ImageDataDiff</span></tt></a>, <a class="reference internal" href="../api/diff.html#astropy.io.fits.TableDataDiff" title="astropy.io.fits.TableDataDiff"><tt class="xref py py-class docutils literal"><span class="pre">TableDataDiff</span></tt></a>, and
<a class="reference internal" href="../api/diff.html#astropy.io.fits.RawDataDiff" title="astropy.io.fits.RawDataDiff"><tt class="xref py py-class docutils literal"><span class="pre">RawDataDiff</span></tt></a>.</p>
<p>Each of these classes are instantiated with two instances of the objects that
they diff. The returned diff instance has a number of attributes starting with
<tt class="docutils literal"><span class="pre">.diff_</span></tt> that describe differences between the two objects.</p>
<p>For example the <a class="reference internal" href="../api/diff.html#astropy.io.fits.HeaderDiff" title="astropy.io.fits.HeaderDiff"><tt class="xref py py-class docutils literal"><span class="pre">HeaderDiff</span></tt></a> class cam be used to find the differences
between two <a class="reference internal" href="../api/headers.html#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-class docutils literal"><span class="pre">Header</span></tt></a> objects like so:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">astropy.io</span> <span class="kn">import</span> <span class="n">fits</span>
<span class="gp">>>> </span><span class="n">header1</span> <span class="o">=</span> <span class="n">fits</span><span class="o">.</span><span class="n">Header</span><span class="p">([(</span><span class="s">'KEY_A'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="p">(</span><span class="s">'KEY_B'</span><span class="p">,</span> <span class="mi">2</span><span class="p">)])</span>
<span class="gp">>>> </span><span class="n">header2</span> <span class="o">=</span> <span class="n">fits</span><span class="o">.</span><span class="n">Header</span><span class="p">([(</span><span class="s">'KEY_A'</span><span class="p">,</span> <span class="mi">3</span><span class="p">),</span> <span class="p">(</span><span class="s">'KEY_C'</span><span class="p">,</span> <span class="mi">4</span><span class="p">)])</span>
<span class="gp">>>> </span><span class="n">diff</span> <span class="o">=</span> <span class="n">fits</span><span class="o">.</span><span class="n">diff</span><span class="o">.</span><span class="n">HeaderDiff</span><span class="p">(</span><span class="n">header1</span><span class="p">,</span> <span class="n">header2</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">diff</span><span class="o">.</span><span class="n">identical</span>
<span class="go">False</span>
<span class="gp">>>> </span><span class="n">diff</span><span class="o">.</span><span class="n">diff_keywords</span>
<span class="go">(['KEY_B'], ['KEY_C'])</span>
<span class="gp">>>> </span><span class="n">diff</span><span class="o">.</span><span class="n">diff_keyword_values</span>
<span class="go">defaultdict(<function <lambda> at ...>, {'KEY_A': [(1, 3)]})</span>
</pre></div>
</div>
<p>See the API documentation for details on the different differ classes.</p>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar">
<div class="sphinxsidebarwrapper"><h3>Page Contents</h3>
<ul>
<li><a class="reference internal" href="#">Miscellaneous Features</a><ul>
<li><a class="reference internal" href="#differs">Differs</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div class="clearer"></div>
</div>
<footer class="footer">
<p class="pull-right">
<a href="http://github.com/astropy/astropy/tree/v0.2.4/docs/io/fits/usage/misc.rst">Edit This Page on Github</a>
<a href="../../../_sources/io/fits/usage/misc.txt"
rel="nofollow">Page Source</a>
<a href="#">Back to Top</a></p>
<p>
© Copyright 2011-2013, The Astropy Developers.<br/>
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.1.3.
Last built 22 Oct 2013. <br/>
</p>
</footer>
</body>
</html>
