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<title>Check if a variable qualifies as a key — isKey • dataMaid</title>

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is a key, that is, if every observation has a unique value in v and 
v is not a numeric/integer nor a Date variable. This
function is intended for use as a precheck in makeDataReport." />
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    <h1>Check if a variable qualifies as a key</h1>
    <small class="dont-index">Source: <a href='https://github.com/ekstroem/dataMaid/blob/master/R/isKey.R'><code>R/isKey.R</code></a></small>
    <div class="hidden name"><code>isKey.Rd</code></div>
    </div>

    <div class="ref-description">
    
    <p>A <code><a href='checkFunction.html'>checkFunction</a></code> that checks if <code>v</code> 
is a key, that is, if every observation has a unique value in <code>v</code> and 
<code>v</code> is not a numeric/integer nor a Date variable. This
function is intended for use as a precheck in <code><a href='makeDataReport.html'>makeDataReport</a></code>.</p>
    
    </div>

    <pre class="usage"><span class='fu'>isKey</span>(<span class='no'>v</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>v</th>
      <td><p>A variable (vector) to check. All variable types are allowed.</p></td>
    </tr>
    </table>
    
    <h2 class="hasAnchor" id="value"><a class="anchor" href="#value"></a>Value</h2>

    <p>A <code><a href='checkResult.html'>checkResult</a></code> with three entires: 
<code>$problem</code> (a logical indicating whether <code>v</code> is a key),
<code>$message</code> (if a problem was found, the following message: 
"The variable is a key (distinct values for each observation).", 
otherwise "") and <code>$problemValues</code> (always <code>NULL</code>).</p>
    
    <h2 class="hasAnchor" id="details"><a class="anchor" href="#details"></a>Details</h2>

    <p>Note that numeric or integer variables are not considered candidates 
for keys, as truly continuous measurements will most likely result in unique 
values for each observation.</p>
    
    <h2 class="hasAnchor" id="see-also"><a class="anchor" href="#see-also"></a>See also</h2>

    <div class='dont-index'><p><code><a href='check.html'>check</a></code>, <code><a href='allCheckFunctions.html'>allCheckFunctions</a></code>, 
<code><a href='checkFunction.html'>checkFunction</a></code>, <code><a href='checkResult.html'>checkResult</a></code></p></div>
    

    <h2 class="hasAnchor" id="examples"><a class="anchor" href="#examples"></a>Examples</h2>
    <pre class="examples"><div class='input'><span class='no'>keyVar</span> <span class='kw'>&lt;-</span> <span class='fu'>c</span>(<span class='st'>"a"</span>, <span class='st'>"b"</span>, <span class='st'>"c"</span>, <span class='st'>"d"</span>, <span class='st'>"e"</span>, <span class='st'>"f"</span>)
<span class='no'>notKeyVar</span> <span class='kw'>&lt;-</span> <span class='fu'>c</span>(<span class='st'>"a"</span>, <span class='st'>"a"</span>, <span class='st'>"b"</span>, <span class='st'>"c"</span>, <span class='st'>"d"</span>, <span class='st'>"e"</span>, <span class='st'>"f"</span>)

<span class='fu'>isKey</span>(<span class='no'>keyVar</span>)</div><div class='output co'>#&gt; The variable is a key (distinct values for each observation).</div><div class='input'><span class='fu'>isKey</span>(<span class='no'>notKeyVar</span>)</div><div class='output co'>#&gt; No problems found.</div><div class='input'>
</div></pre>
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  <div class="col-md-3 hidden-xs hidden-sm" id="sidebar">
    <h2>Contents</h2>
    <ul class="nav nav-pills nav-stacked">
      <li><a href="#arguments">Arguments</a></li>
      
      <li><a href="#value">Value</a></li>

      <li><a href="#details">Details</a></li>

      <li><a href="#see-also">See also</a></li>
      
      <li><a href="#examples">Examples</a></li>
    </ul>

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