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<div class="section" id="units">

<h1>units<a class="headerlink" href="#units" title="Permalink to this headline">¶</a></h1>

<div class="section" id="module-matplotlib.units">

<span id="matplotlib-units"></span><h2><a class="reference internal" href="#module-matplotlib.units" title="matplotlib.units"><code class="xref py py-mod docutils literal"><span class="pre">matplotlib.units</span></code></a><a class="headerlink" href="#module-matplotlib.units" title="Permalink to this headline">¶</a></h2>

<p>The classes here provide support for using custom classes with

matplotlib, e.g., those that do not expose the array interface but know

how to converter themselves to arrays. It also supoprts classes with

units and units conversion. Use cases include converters for custom

objects, e.g., a list of datetime objects, as well as for objects that

are unit aware. We don&#8217;t assume any particular units implementation,

rather a units implementation must provide a ConversionInterface, and

the register with the Registry converter dictionary. For example,

here is a complete implementation which supports plotting with native

datetime objects:</p>

<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">matplotlib.units</span> <span class="k">as</span> <span class="nn">units</span>

<span class="kn">import</span> <span class="nn">matplotlib.dates</span> <span class="k">as</span> <span class="nn">dates</span>

<span class="kn">import</span> <span class="nn">matplotlib.ticker</span> <span class="k">as</span> <span class="nn">ticker</span>

<span class="kn">import</span> <span class="nn">datetime</span>

<span class="k">class</span> <span class="nc">DateConverter</span><span class="p">(</span><span class="n">units</span><span class="o">.</span><span class="n">ConversionInterface</span><span class="p">):</span>

<span class="nd">@staticmethod</span>

<span class="k">def</span> <span class="nf">convert</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">unit</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>

<span class="s1">&#39;convert value to a scalar or array&#39;</span>

<span class="k">return</span> <span class="n">dates</span><span class="o">.</span><span class="n">date2num</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>

<span class="nd">@staticmethod</span>

<span class="k">def</span> <span class="nf">axisinfo</span><span class="p">(</span><span class="n">unit</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>

<span class="s1">&#39;return major and minor tick locators and formatters&#39;</span>

<span class="k">if</span> <span class="n">unit</span><span class="o">!=</span><span class="s1">&#39;date&#39;</span><span class="p">:</span> <span class="k">return</span> <span class="kc">None</span>

<span class="n">majloc</span> <span class="o">=</span> <span class="n">dates</span><span class="o">.</span><span class="n">AutoDateLocator</span><span class="p">()</span>

<span class="n">majfmt</span> <span class="o">=</span> <span class="n">dates</span><span class="o">.</span><span class="n">AutoDateFormatter</span><span class="p">(</span><span class="n">majloc</span><span class="p">)</span>

<span class="k">return</span> <span class="n">AxisInfo</span><span class="p">(</span><span class="n">majloc</span><span class="o">=</span><span class="n">majloc</span><span class="p">,</span>

<span class="n">majfmt</span><span class="o">=</span><span class="n">majfmt</span><span class="p">,</span>

<span class="n">label</span><span class="o">=</span><span class="s1">&#39;date&#39;</span><span class="p">)</span>

<span class="nd">@staticmethod</span>

<span class="k">def</span> <span class="nf">default_units</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>

<span class="s1">&#39;return the default unit for x or None&#39;</span>

<span class="k">return</span> <span class="s1">&#39;date&#39;</span>

<span class="c1"># finally we register our object type with a converter</span>

<span class="n">units</span><span class="o">.</span><span class="n">registry</span><span class="p">[</span><span class="n">datetime</span><span class="o">.</span><span class="n">date</span><span class="p">]</span> <span class="o">=</span> <span class="n">DateConverter</span><span class="p">()</span>

<dl class="class">

<dt id="matplotlib.units.AxisInfo">

<em class="property">class </em><code class="descclassname">matplotlib.units.</code><code class="descname">AxisInfo</code><span class="sig-paren">(</span><em>majloc=None</em>, <em>minloc=None</em>, <em>majfmt=None</em>, <em>minfmt=None</em>, <em>label=None</em>, <em>default_limits=None</em><span class="sig-paren">)</span><a class="headerlink" href="#matplotlib.units.AxisInfo" title="Permalink to this definition">¶</a></dt>

<dd><p>Bases: <code class="xref py py-class docutils literal"><span class="pre">object</span></code></p>

<p>information to support default axis labeling and tick labeling, and

default limits</p>

<p>majloc and minloc: TickLocators for the major and minor ticks

majfmt and minfmt: TickFormatters for the major and minor ticks

label: the default axis label

default_limits: the default min, max of the axis if no data is present

If any of the above are None, the axis will simply use the default</p>

<dl class="class">

<dt id="matplotlib.units.ConversionInterface">

<em class="property">class </em><code class="descclassname">matplotlib.units.</code><code class="descname">ConversionInterface</code><a class="headerlink" href="#matplotlib.units.ConversionInterface" title="Permalink to this definition">¶</a></dt>

<dd><p>Bases: <code class="xref py py-class docutils literal"><span class="pre">object</span></code></p>

<p>The minimal interface for a converter to take custom instances (or

sequences) and convert them to values mpl can use</p>

<dl class="staticmethod">

<dt id="matplotlib.units.ConversionInterface.axisinfo">

<em class="property">static </em><code class="descname">axisinfo</code><span class="sig-paren">(</span><em>unit</em>, <em>axis</em><span class="sig-paren">)</span><a class="headerlink" href="#matplotlib.units.ConversionInterface.axisinfo" title="Permalink to this definition">¶</a></dt>

<dd><p>return an units.AxisInfo instance for axis with the specified units</p>

<dl class="staticmethod">

<dt id="matplotlib.units.ConversionInterface.convert">

<em class="property">static </em><code class="descname">convert</code><span class="sig-paren">(</span><em>obj</em>, <em>unit</em>, <em>axis</em><span class="sig-paren">)</span><a class="headerlink" href="#matplotlib.units.ConversionInterface.convert" title="Permalink to this definition">¶</a></dt>

<dd><p>convert obj using unit for the specified axis. If obj is a sequence,

return the converted sequence. The ouput must be a sequence of scalars

that can be used by the numpy array layer</p>

<dl class="staticmethod">

<dt id="matplotlib.units.ConversionInterface.default_units">

<em class="property">static </em><code class="descname">default_units</code><span class="sig-paren">(</span><em>x</em>, <em>axis</em><span class="sig-paren">)</span><a class="headerlink" href="#matplotlib.units.ConversionInterface.default_units" title="Permalink to this definition">¶</a></dt>

<dd><p>return the default unit for x or None for the given axis</p>

<dl class="staticmethod">

<dt id="matplotlib.units.ConversionInterface.is_numlike">

<em class="property">static </em><code class="descname">is_numlike</code><span class="sig-paren">(</span><em>x</em><span class="sig-paren">)</span><a class="headerlink" href="#matplotlib.units.ConversionInterface.is_numlike" title="Permalink to this definition">¶</a></dt>

<dd><p>The matplotlib datalim, autoscaling, locators etc work with

scalars which are the units converted to floats given the

current unit. The converter may be passed these floats, or

arrays of them, even when units are set. Derived conversion

interfaces may opt to pass plain-ol unitless numbers through

the conversion interface and this is a helper function for

them.</p>

<dl class="class">

<dt id="matplotlib.units.Registry">

<em class="property">class </em><code class="descclassname">matplotlib.units.</code><code class="descname">Registry</code><a class="headerlink" href="#matplotlib.units.Registry" title="Permalink to this definition">¶</a></dt>

<dd><p>Bases: <code class="xref py py-class docutils literal"><span class="pre">dict</span></code></p>

<p>register types with conversion interface</p>

<dl class="method">

<dt id="matplotlib.units.Registry.get_converter">

<code class="descname">get_converter</code><span class="sig-paren">(</span><em>x</em><span class="sig-paren">)</span><a class="headerlink" href="#matplotlib.units.Registry.get_converter" title="Permalink to this definition">¶</a></dt>

<dd><p>get the converter interface instance for x, or None</p>

</div>

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