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<meta property="og:title" content="Statistical transformation for rasters — raster.transformation" />
<meta property="og:description" content="Transforms raster to a specified statistical transformation
Transformation option details:
norm - (Normalization_ (0-1): if min(x) &amp;lt; 0 ( x - min(x) ) / ( max(x) - min(x) )
rstd - (Row standardize) (0-1): if min(x) &amp;gt;= 0 x / max(x) This normalizes data
   with negative distributions

std - (Standardize) (x - mean(x)) / sdv(x)
stretch - (Stretch) ((x - min(x)) * max.stretch / (max(x) - min(x)) + min.stretch)
This will stretch values to the specified minimum and maximum values
(eg., 0-255 for 8-bit)
nl - (Natural logarithms) if min(x) &amp;gt; 0 log(x)
slog - (Signed log 10) (for skewed data): if min(x) &amp;gt;= 0 ifelse(abs(x) &amp;lt;= 1, 0,
sign(x)*log10(abs(x)))
sr - (Square-root) if min(x) &amp;gt;= 0 sqrt(x)

" />




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    <h1>Statistical transformation for rasters</h1>
    <small class="dont-index">Source: <a href='https://github.com/jeffreyevans/spatialEco/blob/master/R/raster.transformations.R'><code>R/raster.transformations.R</code></a></small>
    <div class="hidden name"><code>raster.transformation.Rd</code></div>
    </div>

    <div class="ref-description">
    <p>Transforms raster to a specified statistical transformation</p>
<p>Transformation option details:</p><ul>
<li><p>norm - (Normalization_ (0-1): if min(x) &lt; 0 ( x - min(x) ) / ( max(x) - min(x) )</p></li>
<li><p>rstd - (Row standardize) (0-1): if min(x) &gt;= 0 x / max(x) This normalizes data</p></li>
<li><p></p><pre>   with negative distributions
</pre></li>
<li><p>std - (Standardize) (x - mean(x)) / sdv(x)</p></li>
<li><p>stretch - (Stretch) ((x - min(x)) * max.stretch / (max(x) - min(x)) + min.stretch)
This will stretch values to the specified minimum and maximum values
(eg., 0-255 for 8-bit)</p></li>
<li><p>nl - (Natural logarithms) if min(x) &gt; 0 log(x)</p></li>
<li><p>slog - (Signed log 10) (for skewed data): if min(x) &gt;= 0 ifelse(abs(x) &lt;= 1, 0,
sign(x)*log10(abs(x)))</p></li>
<li><p>sr - (Square-root) if min(x) &gt;= 0 sqrt(x)</p></li>
</ul>

    </div>

    <pre class="usage"><span class='fu'>raster.transformation</span><span class='op'>(</span><span class='va'>x</span>, trans <span class='op'>=</span> <span class='st'>"norm"</span>, smin <span class='op'>=</span> <span class='fl'>0</span>, smax <span class='op'>=</span> <span class='fl'>255</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>raster class object</p></td>
    </tr>
    <tr>
      <th>trans</th>
      <td><p>Transformation method: "norm", "rstd", "std", "stretch",
"nl", "slog", "sr" (please see notes)</p></td>
    </tr>
    <tr>
      <th>smin</th>
      <td><p>Minimum value for stretch</p></td>
    </tr>
    <tr>
      <th>smax</th>
      <td><p>Maximum value for stretch</p></td>
    </tr>
    </table>

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

    <p>raster class object of transformation</p>
    <h2 class="hasAnchor" id="author"><a class="anchor" href="#author"></a>Author</h2>

    <p>Jeffrey S. Evans  <a href='mailto:jeffrey_evans@tnc.org'>jeffrey_evans@tnc.org</a></p>

    <h2 class="hasAnchor" id="examples"><a class="anchor" href="#examples"></a>Examples</h2>
    <pre class="examples"><div class='input'><span class='co'># \donttest{</span>
  <span class='kw'><a href='https://rdrr.io/r/base/library.html'>library</a></span><span class='op'>(</span><span class='va'><a href='https://rspatial.org/raster'>raster</a></span><span class='op'>)</span>
  <span class='va'>r</span> <span class='op'>&lt;-</span> <span class='fu'><a href='https://rdrr.io/pkg/raster/man/raster.html'>raster</a></span><span class='op'>(</span>nrows<span class='op'>=</span><span class='fl'>100</span>, ncols<span class='op'>=</span><span class='fl'>100</span>, xmn<span class='op'>=</span><span class='fl'>571823</span>, xmx<span class='op'>=</span><span class='fl'>616763</span>, 
              ymn<span class='op'>=</span><span class='fl'>4423540</span>, ymx<span class='op'>=</span><span class='fl'>4453690</span><span class='op'>)</span>
    <span class='va'>r</span><span class='op'>[</span><span class='op'>]</span> <span class='op'>&lt;-</span> <span class='fu'><a href='https://rdrr.io/r/stats/Uniform.html'>runif</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/pkg/raster/man/ncell.html'>ncell</a></span><span class='op'>(</span><span class='va'>r</span><span class='op'>)</span>, <span class='fl'>1000</span>, <span class='fl'>2500</span><span class='op'>)</span>

 <span class='co'># Postive values so, can apply any transformation    </span>
<span class='kw'>for</span><span class='op'>(</span> <span class='va'>i</span> <span class='kw'>in</span> <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='st'>"norm"</span>, <span class='st'>"rstd"</span>, <span class='st'>"std"</span>, <span class='st'>"stretch"</span>, <span class='st'>"nl"</span>, <span class='st'>"slog"</span>, <span class='st'>"sr"</span><span class='op'>)</span><span class='op'>)</span> <span class='op'>{</span>
  <span class='fu'><a href='https://rdrr.io/r/base/print.html'>print</a></span><span class='op'>(</span> <span class='fu'>raster.transformation</span><span class='op'>(</span><span class='va'>r</span>, trans <span class='op'>=</span> <span class='va'>i</span><span class='op'>)</span> <span class='op'>)</span> 
   <span class='op'>}</span>
</div><div class='output co'>#&gt; <span class='message'>applying normalization transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 0, 1  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying row-standardization transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 0.40009, 1  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying standardization transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : -1.739012, 1.722989  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying stretch transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 0, 255  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying log transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 6.907824, 7.823889  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying singned-log10 transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 3.00003, 3.397872  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying sqare-root transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 31.62386, 49.99609  (min, max)
#&gt; </div><div class='input'>
 <span class='co'># Negative values so, can't transform using "nl", "slog" or "sr"</span>
<span class='va'>r</span><span class='op'>[</span><span class='op'>]</span> <span class='op'>&lt;-</span> <span class='fu'><a href='https://rdrr.io/r/stats/Uniform.html'>runif</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/pkg/raster/man/ncell.html'>ncell</a></span><span class='op'>(</span><span class='va'>r</span><span class='op'>)</span>, <span class='op'>-</span><span class='fl'>1</span>, <span class='fl'>1</span><span class='op'>)</span>
   <span class='kw'>for</span><span class='op'>(</span> <span class='va'>i</span> <span class='kw'>in</span> <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='st'>"norm"</span>, <span class='st'>"rstd"</span>, <span class='st'>"std"</span>, <span class='st'>"stretch"</span>, <span class='st'>"nl"</span>, <span class='st'>"slog"</span>, <span class='st'>"sr"</span><span class='op'>)</span><span class='op'>)</span> <span class='op'>{</span>
  <span class='kw'><a href='https://rdrr.io/r/base/try.html'>try</a></span><span class='op'>(</span> <span class='fu'><a href='https://rdrr.io/r/base/print.html'>print</a></span><span class='op'>(</span> <span class='fu'>raster.transformation</span><span class='op'>(</span><span class='va'>r</span>, trans <span class='op'>=</span> <span class='va'>i</span><span class='op'>)</span> <span class='op'>)</span> <span class='op'>)</span> 
   <span class='op'>}</span>
</div><div class='output co'>#&gt; [1] " Min value &lt; 0, running row standardization instead"
#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : -1.000017, 1  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying row-standardization transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : -1.000017, 1  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying standardization transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : -1.718704, 1.742859  (min, max)
#&gt; </div><div class='output co'>#&gt; <span class='message'>applying stretch transformation</span></div><div class='output co'>#&gt; class      : RasterLayer 
#&gt; dimensions : 100, 100, 10000  (nrow, ncol, ncell)
#&gt; resolution : 449.4, 301.5  (x, y)
#&gt; extent     : 571823, 616763, 4423540, 4453690  (xmin, xmax, ymin, ymax)
#&gt; crs        : NA 
#&gt; source     : memory
#&gt; names      : layer 
#&gt; values     : 0, 255  (min, max)
#&gt; 
#&gt; Error in h(simpleError(msg, call)) : 
#&gt;   error in evaluating the argument 'x' in selecting a method for function 'print':  Minimum value &lt; 0, cannot log transform
#&gt; Error in h(simpleError(msg, call)) : 
#&gt;   error in evaluating the argument 'x' in selecting a method for function 'print':  Minimum value &lt; 0, cannot log transform
#&gt; Error in h(simpleError(msg, call)) : 
#&gt;   error in evaluating the argument 'x' in selecting a method for function 'print':  Minimum value &lt; 0, cannot log transform</div><div class='input'><span class='co'># }</span>

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