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  26 <a name="boost.histogram.indexed"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Function template indexed</span></h2>
  29 <p>boost::histogram::indexed &#8212; Generates an indexed range of <a href="https://en.cppreference.com/w/cpp/named_req/ForwardIterator" target="_top">forward iterators</a> over the histogram cells. </p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../histogram/reference.html#header.boost.histogram.indexed_hpp" title="Header &lt;boost/histogram/indexed.hpp&gt;">boost/histogram/indexed.hpp</a>&gt;
  33
  34 </span>
  35 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Histogram<span class="special">&gt;</span>
  36   <span class="keyword">auto</span> <span class="identifier">indexed</span><span class="special">(</span><span class="identifier">Histogram</span> <span class="special">&amp;&amp;</span> hist<span class="special">,</span> <span class="identifier">coverage</span> cov <span class="special">=</span> <span class="identifier">coverage</span><span class="special">::</span><span class="identifier">inner</span><span class="special">)</span><span class="special">;</span></pre></div>
  37 <div class="refsect1">
  38 <a name="idm45212143092432"></a><h2>Description</h2>
  39 <p>Use this in a range-based for loop:</p>
  40 <pre class="programlisting"><span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span><span class="special">&amp;&amp;</span> <span class="identifier">x</span> <span class="special">:</span> <span class="identifier">indexed</span><span class="special">(</span><span class="identifier">hist</span><span class="special">)</span><span class="special">)</span> <span class="special">{</span> <span class="special">...</span> <span class="special">}</span>
  41 </pre>
  42 <p>This generates an optimized loop which is nearly always faster than a hand-written loop over the histogram cells. The iterators dereference to an <code class="computeroutput"><a class="link" href="indexed_range/accessor.html" title="Class accessor">indexed_range::accessor</a></code>, which has methods to query the current indices and bins and acts like a pointer to the cell value. The returned iterators are forward iterators. They can be stored in a container, but may not be used after the life-time of the histogram ends.</p>
  43 <p>
  44
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  46 <div class="variablelist"><table border="0" class="variablelist compact">
  47 <colgroup>
  48 <col align="left" valign="top">
  49 <col>
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  51 <tbody>
  52 <tr>
  53 <td><p><span class="term">Parameters:</span></p></td>
  54 <td><div class="variablelist"><table border="0" class="variablelist compact">
  55 <colgroup>
  56 <col align="left" valign="top">
  57 <col>
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  59 <tbody>
  60 <tr>
  61 <td><p><span class="term"><code class="computeroutput">cov</code></span></p></td>
  62 <td><p>Iterate over all or only inner bins (optional, default: inner). </p></td>
  63 </tr>
  64 <tr>
  65 <td><p><span class="term"><code class="computeroutput">hist</code></span></p></td>
  66 <td><p>Reference to the histogram. </p></td>
  67 </tr>
  68 </tbody>
  69 </table></div></td>
  70 </tr>
  71 <tr>
  72 <td><p><span class="term">Returns:</span></p></td>
  73 <td><p><a class="link" href="indexed_range.html" title="Class template indexed_range">indexed_range</a></p></td>
  74 </tr>
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