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  <div class="section" id="dtype">
<h1><a class="toc-backref" href="#id2">dtype</a></h1>
<div class="contents topic" id="table-of-contents">
<p class="topic-title first">Table of Contents</p>
<ul class="simple">
<li><a class="reference internal" href="#dtype" id="id2">dtype</a><ul>
<li><a class="reference internal" href="#synopsis" id="id3">synopsis</a></li>
<li><a class="reference internal" href="#constructors" id="id4">constructors</a></li>
<li><a class="reference internal" href="#accessors" id="id5">accessors</a></li>
<li><a class="reference internal" href="#example-s" id="id6">Example(s)</a></li>
</ul>
</li>
</ul>
</div>
<p>A <a class="reference external" href="http://docs.scipy.org/doc/numpy/reference/arrays.dtypes.html#data-type-objects-dtype">dtype</a> is an object describing the type of the elements of an ndarray</p>
<blockquote>
<div><code class="docutils literal"><span class="pre">&lt;boost/python/numpy/dtype.hpp&gt;</span></code> contains the method calls necessary to generate a python object equivalent to a numpy.dtype from builtin C++ objects, as well as to create custom dtypes from user defined types</div></blockquote>
<div class="section" id="synopsis">
<h2><a class="toc-backref" href="#id3">synopsis</a></h2>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">namespace</span> <span class="n">boost</span>
<span class="p">{</span>
<span class="k">namespace</span> <span class="n">python</span>
<span class="p">{</span>
<span class="k">namespace</span> <span class="n">numpy</span>
<span class="p">{</span>

<span class="k">class</span> <span class="nc">dtype</span> <span class="o">:</span> <span class="k">public</span> <span class="n">object</span>
<span class="p">{</span>
  <span class="k">static</span> <span class="n">python</span><span class="o">::</span><span class="n">detail</span><span class="o">::</span><span class="n">new_reference</span> <span class="n">convert</span><span class="p">(</span><span class="n">object</span><span class="o">::</span><span class="n">object_cref</span> <span class="n">arg</span><span class="p">,</span> <span class="kt">bool</span> <span class="n">align</span><span class="p">);</span>
<span class="k">public</span><span class="o">:</span>

  <span class="c1">// Convert an arbitrary Python object to a data-type descriptor object.</span>
  <span class="k">template</span> <span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span>
  <span class="k">explicit</span> <span class="n">dtype</span><span class="p">(</span><span class="n">T</span> <span class="n">arg</span><span class="p">,</span> <span class="kt">bool</span> <span class="n">align</span><span class="o">=</span><span class="nb">false</span><span class="p">);</span>

  <span class="c1">// Get the built-in numpy dtype associated with the given scalar template type.</span>
  <span class="k">template</span> <span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span> <span class="k">static</span> <span class="n">dtype</span> <span class="n">get_builtin</span><span class="p">();</span>

  <span class="c1">// Return the size of the data type in bytes.</span>
  <span class="kt">int</span> <span class="nf">get_itemsize</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
<span class="p">};</span>

<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="constructors">
<h2><a class="toc-backref" href="#id4">constructors</a></h2>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">template</span> <span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span>
<span class="k">explicit</span> <span class="n">dtype</span><span class="p">(</span><span class="n">T</span> <span class="n">arg</span><span class="p">,</span> <span class="kt">bool</span> <span class="n">align</span><span class="o">=</span><span class="nb">false</span><span class="p">)</span>
</pre></div>
</div>
<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">Requirements:</th><td class="field-body"><p class="first"><code class="docutils literal"><span class="pre">T</span></code> must be either :</p>
<ul class="simple">
<li>a built-in C++ typename convertible to object</li>
<li>a valid python object or convertible to object</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Effects:</th><td class="field-body"><p class="first">Constructs an object from the supplied python object / convertible
to object / builtin C++ data type</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Throws:</th><td class="field-body"><p class="first last">Nothing</p>
</td>
</tr>
</tbody>
</table>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">template</span> <span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span> <span class="k">static</span> <span class="n">dtype</span> <span class="n">get_builtin</span><span class="p">();</span>
</pre></div>
</div>
<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">Requirements:</th><td class="field-body">The typename supplied, <code class="docutils literal"><span class="pre">T</span></code> must be a builtin C++ type also supported by numpy</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">Numpy dtype corresponding to builtin C++ type</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="accessors">
<h2><a class="toc-backref" href="#id5">accessors</a></h2>
<div class="highlight-c++"><div class="highlight"><pre><span class="kt">int</span> <span class="nf">get_itemsize</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<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">Returns:</th><td class="field-body">the size of the data type in bytes.</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="example-s">
<h2><a class="toc-backref" href="#id6">Example(s)</a></h2>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">namespace</span> <span class="n">p</span> <span class="o">=</span> <span class="n">boost</span><span class="o">::</span><span class="n">python</span><span class="p">;</span>
<span class="k">namespace</span> <span class="n">np</span> <span class="o">=</span> <span class="n">boost</span><span class="o">::</span><span class="n">python</span><span class="o">::</span><span class="n">numpy</span><span class="p">;</span>

<span class="n">np</span><span class="o">::</span><span class="n">dtype</span> <span class="n">dtype</span> <span class="o">=</span> <span class="n">np</span><span class="o">::</span><span class="n">dtype</span><span class="o">::</span><span class="n">get_builtin</span><span class="o">&lt;</span><span class="kt">double</span><span class="o">&gt;</span><span class="p">();</span>
<span class="n">p</span><span class="o">::</span><span class="n">tuple</span> <span class="n">for_custom_dtype</span> <span class="o">=</span> <span class="n">p</span><span class="o">::</span><span class="n">make_tuple</span><span class="p">(</span><span class="s">&quot;ha&quot;</span><span class="p">,</span><span class="n">dtype</span><span class="p">);</span>
<span class="n">np</span><span class="o">::</span><span class="n">dtype</span> <span class="n">custom_dtype</span> <span class="o">=</span> <span class="n">np</span><span class="o">::</span><span class="n">dtype</span><span class="p">(</span><span class="n">list_for_dtype</span><span class="p">);</span>
</pre></div>
</div>
</div>
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