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of the sampling, and that the clock drifts linearly (i.e. is uniformly fast
or slow) over the sampling interval.  Linear interpolation is used to infer
the values of all variables in the data slot.  The data length is
altered in this process, e.g. a slow instrument clock (positive
slowEnd) takes too few samples in a given time interval, so
undriftTime will increase the number of data."><meta property="og:description" content="It is assumed that the instrument clock matches the real time at the start
of the sampling, and that the clock drifts linearly (i.e. is uniformly fast
or slow) over the sampling interval.  Linear interpolation is used to infer
the values of all variables in the data slot.  The data length is
altered in this process, e.g. a slow instrument clock (positive
slowEnd) takes too few samples in a given time interval, so
undriftTime will increase the number of data."></head><body>
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      <h1>Correct for Drift in an Instrument Clock</h1>
      <small class="dont-index">Source: <a href="https://github.com/dankelley/oce/blob/HEAD/R/misc.R" class="external-link"><code>R/misc.R</code></a></small>
      <div class="d-none name"><code>undriftTime.Rd</code></div>
    </div>

    <div class="ref-description section level2">
    <p>It is assumed that the instrument clock matches the real time at the start
of the sampling, and that the clock drifts linearly (i.e. is uniformly fast
or slow) over the sampling interval.  Linear interpolation is used to infer
the values of all variables in the <code>data</code> slot.  The data length is
altered in this process, e.g. a slow instrument clock (positive
<code>slowEnd</code>) takes too few samples in a given time interval, so
<code>undriftTime</code> will increase the number of data.</p>
    </div>

    <div class="section level2">
    <h2 id="ref-usage">Usage<a class="anchor" aria-label="anchor" href="#ref-usage"></a></h2>
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">undriftTime</span><span class="op">(</span><span class="va">x</span>, slowEnd <span class="op">=</span> <span class="fl">0</span>, tname <span class="op">=</span> <span class="st">"time"</span><span class="op">)</span></span></code></pre></div>
    </div>

    <div class="section level2">
    <h2 id="arguments">Arguments<a class="anchor" aria-label="anchor" href="#arguments"></a></h2>


<dl><dt id="arg-x">x<a class="anchor" aria-label="anchor" href="#arg-x"></a></dt>
<dd><p>an <a href="oce-class.html">oce</a> object.</p></dd>


<dt id="arg-slowend">slowEnd<a class="anchor" aria-label="anchor" href="#arg-slowend"></a></dt>
<dd><p>number of seconds to add to final instrument time, to get the
correct time of the final sample.  This will be a positive number, for a
"slow" instrument clock.</p></dd>


<dt id="arg-tname">tname<a class="anchor" aria-label="anchor" href="#arg-tname"></a></dt>
<dd><p>Character string indicating the name of the time column in the
<code>data</code> slot of <code>x</code>.</p></dd>

</dl></div>
    <div class="section level2">
    <h2 id="value">Value<a class="anchor" aria-label="anchor" href="#value"></a></h2>
    <p>An object of the same class as <code>x</code>, with the <code>data</code> slot
adjusted appropriately.</p>
    </div>
    <div class="section level2">
    <h2 id="sample-of-usage">Sample of Usage<a class="anchor" aria-label="anchor" href="#sample-of-usage"></a></h2>


<div class="sourceCode"><pre><code><span></span>
<span><span class="kw"><a href="https://rdrr.io/r/base/library.html" class="external-link">library</a></span><span class="op">(</span><span class="va"><a href="https://dankelley.github.io/oce/">oce</a></span><span class="op">)</span></span>
<span><span class="va">file</span> <span class="op">&lt;-</span> <span class="st">"~/data/archive/sleiwex/2008/moorings/m08/pt/rbr_011855/raw/pt_rbr_011855.dat"</span></span>
<span><span class="va">rbr011855</span> <span class="op">&lt;-</span> <span class="fu"><a href="../reference/read.oce.html">read.oce</a></span><span class="op">(</span><span class="va">file</span><span class="op">)</span></span>
<span><span class="va">d</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/subset.html" class="external-link">subset</a></span><span class="op">(</span><span class="va">rbr011855</span>, <span class="va">time</span> <span class="op">&lt;</span> <span class="fu"><a href="https://rdrr.io/r/base/as.POSIXlt.html" class="external-link">as.POSIXct</a></span><span class="op">(</span><span class="st">"2008-06-25 10:05:00"</span><span class="op">)</span><span class="op">)</span></span>
<span><span class="va">x</span> <span class="op">&lt;-</span> <span class="fu"><a href="../reference/undriftTime.html">undriftTime</a></span><span class="op">(</span><span class="va">d</span>, <span class="fl">1</span><span class="op">)</span>   <span class="co"># clock lost 1 second over whole experiment</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/base/summary.html" class="external-link">summary</a></span><span class="op">(</span><span class="va">d</span><span class="op">)</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/base/summary.html" class="external-link">summary</a></span><span class="op">(</span><span class="va">x</span><span class="op">)</span></span></code></pre></div>

    </div>
    <div class="section level2">
    <h2 id="author">Author<a class="anchor" aria-label="anchor" href="#author"></a></h2>
    <p>Dan Kelley</p>
    </div>

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