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<title>Percent area sample — parea.sample • spatialEco</title>


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<meta property="og:description" content="Creates a point sample of polygons where n is based 
             on percent area" />




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    <h1>Percent area sample</h1>
    <small class="dont-index">Source: <a href='https://github.com/jeffreyevans/spatialEco/blob/master/R/parea.sample.R'><code>R/parea.sample.R</code></a></small>
    <div class="hidden name"><code>parea.sample.Rd</code></div>
    </div>

    <div class="ref-description">
    <p>Creates a point sample of polygons where n is based 
             on percent area</p>
    </div>

    <pre class="usage"><span class='fu'>parea.sample</span><span class='op'>(</span>
  <span class='va'>x</span>,
  pct <span class='op'>=</span> <span class='fl'>0.1</span>,
  join <span class='op'>=</span> <span class='cn'>FALSE</span>,
  min.samp <span class='op'>=</span> <span class='fl'>1</span>,
  max.samp <span class='op'>=</span> <span class='cn'>NULL</span>,
  sf <span class='op'>=</span> <span class='fl'>4046.86</span>,
  stype <span class='op'>=</span> <span class='st'>"hexagonal"</span>,
  <span class='va'>...</span>
<span class='op'>)</span></pre>

    <h2 class="hasAnchor" id="arguments"><a class="anchor" href="#arguments"></a>Arguments</h2>
    <table class="ref-arguments">
    <colgroup><col class="name" /><col class="desc" /></colgroup>
    <tr>
      <th>x</th>
      <td><p>sp SpatialPolygonsDataFrame object</p></td>
    </tr>
    <tr>
      <th>pct</th>
      <td><p>Percent of area sampled</p></td>
    </tr>
    <tr>
      <th>join</th>
      <td><p>Join polygon attributed to point sample</p></td>
    </tr>
    <tr>
      <th>min.samp</th>
      <td><p>Minimum number of samples</p></td>
    </tr>
    <tr>
      <th>max.samp</th>
      <td><p>Maximum number of samples</p></td>
    </tr>
    <tr>
      <th>sf</th>
      <td><p>Scaling factor (default is meters to acres conversion factor)</p></td>
    </tr>
    <tr>
      <th>stype</th>
      <td><p>Sampling type ('random', 'regular', 'nonaligned', 'hexagonal')</p></td>
    </tr>
    <tr>
      <th>...</th>
      <td><p>Additional arguments passed to spsample</p></td>
    </tr>
    </table>

    <h2 class="hasAnchor" id="value"><a class="anchor" href="#value"></a>Value</h2>

    <p>A SpatialPointsDataFrame with polygon samples</p>
    <h2 class="hasAnchor" id="note"><a class="anchor" href="#note"></a>Note</h2>

    <p>This function results in an adaptive sample based on the area of 
      each polygon</p>
    <h2 class="hasAnchor" id="author"><a class="anchor" href="#author"></a>Author</h2>

    <p>Jeffrey S. Evans  &lt;jeffrey_evans@tnc.org&gt;</p>

    <h2 class="hasAnchor" id="examples"><a class="anchor" href="#examples"></a>Examples</h2>
    <pre class="examples"><div class='input'><span class='kw'><a href='https://rdrr.io/r/base/library.html'>require</a></span><span class='op'>(</span><span class='va'><a href='https://github.com/edzer/sp/'>sp</a></span><span class='op'>)</span>
<span class='va'>sr1</span><span class='op'>=</span><span class='fu'><a href='https://rdrr.io/pkg/sp/man/SpatialPolygons.html'>Polygons</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/list.html'>list</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/pkg/sp/man/SpatialPolygons.html'>Polygon</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/cbind.html'>cbind</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>180114</span>, <span class='fl'>180553</span>, <span class='fl'>181127</span>, <span class='fl'>181477</span>, <span class='fl'>181294</span>, 
  <span class='fl'>181007</span>, <span class='fl'>180409</span>, <span class='fl'>180162</span>, <span class='fl'>180114</span><span class='op'>)</span>, <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>332349</span>, <span class='fl'>332057</span>, <span class='fl'>332342</span>, <span class='fl'>333250</span>, <span class='fl'>333558</span>, 
  <span class='fl'>333676</span>, <span class='fl'>332618</span>, <span class='fl'>332413</span>, <span class='fl'>332349</span><span class='op'>)</span><span class='op'>)</span><span class='op'>)</span><span class='op'>)</span>,<span class='st'>'1'</span><span class='op'>)</span>
<span class='va'>sr2</span><span class='op'>=</span><span class='fu'><a href='https://rdrr.io/pkg/sp/man/SpatialPolygons.html'>Polygons</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/list.html'>list</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/pkg/sp/man/SpatialPolygons.html'>Polygon</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/cbind.html'>cbind</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>180042</span>, <span class='fl'>180545</span>, <span class='fl'>180553</span>, <span class='fl'>180314</span>, <span class='fl'>179955</span>, 
  <span class='fl'>179142</span>, <span class='fl'>179437</span>, <span class='fl'>179524</span>, <span class='fl'>179979</span>, <span class='fl'>180042</span><span class='op'>)</span>, <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>332373</span>, <span class='fl'>332026</span>, <span class='fl'>331426</span>, <span class='fl'>330889</span>, 
  <span class='fl'>330683</span>, <span class='fl'>331133</span>, <span class='fl'>331623</span>, <span class='fl'>332152</span>, <span class='fl'>332357</span>, <span class='fl'>332373</span><span class='op'>)</span><span class='op'>)</span><span class='op'>)</span><span class='op'>)</span>,<span class='st'>'2'</span><span class='op'>)</span>
<span class='va'>sr</span><span class='op'>=</span><span class='fu'><a href='https://rdrr.io/pkg/sp/man/SpatialPolygons.html'>SpatialPolygons</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/list.html'>list</a></span><span class='op'>(</span><span class='va'>sr1</span>,<span class='va'>sr2</span><span class='op'>)</span><span class='op'>)</span>
<span class='va'>srdf</span><span class='op'>=</span><span class='fu'><a href='https://rdrr.io/pkg/sp/man/SpatialPolygons.html'>SpatialPolygonsDataFrame</a></span><span class='op'>(</span><span class='va'>sr</span>, <span class='fu'><a href='https://rdrr.io/r/base/data.frame.html'>data.frame</a></span><span class='op'>(</span>row.names<span class='op'>=</span><span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='st'>'1'</span>,<span class='st'>'2'</span><span class='op'>)</span>, PIDS<span class='op'>=</span><span class='fl'>1</span><span class='op'>:</span><span class='fl'>2</span><span class='op'>)</span><span class='op'>)</span>

<span class='va'>ars</span> <span class='op'>&lt;-</span> <span class='fu'>parea.sample</span><span class='op'>(</span><span class='va'>srdf</span>, pct<span class='op'>=</span><span class='fl'>0.20</span>, stype<span class='op'>=</span><span class='st'>'random'</span><span class='op'>)</span> 
</div><div class='output co'>#&gt; sampling 1 of 2 
#&gt; sampling 2 of 2 </div><div class='input'>  <span class='fu'><a href='https://rdrr.io/pkg/raster/man/plot.html'>plot</a></span><span class='op'>(</span><span class='va'>srdf</span><span class='op'>)</span>
</div><div class='input'>    <span class='fu'><a href='https://rdrr.io/pkg/raster/man/plot.html'>plot</a></span><span class='op'>(</span><span class='va'>ars</span>, pch<span class='op'>=</span><span class='fl'>20</span>, add<span class='op'>=</span><span class='cn'>TRUE</span><span class='op'>)</span>
</div><div class='img'><img src='parea.sample-1.png' alt='' width='700' height='433' /></div><div class='input'>
</div></pre>
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