From 05517003081129c6aacf50b986db0cf01d9d1fa7 Mon Sep 17 00:00:00 2001
From: Andy Lyons <lyons.andy@gmail.com>
Date: Fri, 10 Nov 2023 10:23:48 -0800
Subject: [PATCH] Small update to Pt4 Slides

---
 slides/slides_pt4.html | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/slides/slides_pt4.html b/slides/slides_pt4.html
index 0312d17..f7d183c 100644
--- a/slides/slides_pt4.html
+++ b/slides/slides_pt4.html
@@ -511,8 +511,8 @@ <h2 id="combine-datetime-parts">Combine Date/Time Parts</h2>
 <p><br />
 </p>
 </div>
-<div id="missing-data" class="slide section level1">
-<h1>Missing Data</h1>
+<div id="dealing-with-missing-data" class="slide section level1">
+<h1>Dealing with Missing Data</h1>
 <style type="text/css">
 span.mono {
   font-family: monospace;
@@ -565,7 +565,6 @@ <h3 id="option-4-replace-missing-values-with-another-column">Option 4:
 if_else(…)</span><span class="gray"> )</span></span></p>
 <p><span class="mono"><span class="gray">mutate( </span>new_col =
 coalesce(…)</span><span class="gray"> )</span></span></p>
-<p><span class="mono">tidyr::replace_na()</span></p>
 </div>
 <p><br />
 </p>
@@ -650,6 +649,14 @@ <h2 id="chaing-the-default-time-zone-on-posit-cloud">Chaing the Default
 </div>
 <p><br />
 </p>
+<h2 id="lags-and-leads">Lags and Leads</h2>
+<p>To create a new column which includes lagged values, you can use</p>
+<div class="indented2" style="font-family:monospace;">
+<p>lag()</p>
+<p>lead()</p>
+</div>
+<p><br />
+</p>
 <h2 id="saving-date-times-to-disk">Saving Date-Times to Disk</h2>
 <div class="indented2">
 
@@ -679,7 +686,7 @@ <h2 id="saving-date-times-to-disk">Saving Date-Times to Disk</h2>
 </div>
 <div class="indented2 indented2r">
 <div class="sourceCode" id="cb24"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="fu">format</span>(<span class="fu">Sys.Date</span>(), <span class="st">&quot;%Y-%m-%d&quot;</span>)</span></code></pre></div>
-<pre><code>## [1] &quot;2023-10-30&quot;</code></pre>
+<pre><code>## [1] &quot;2023-11-10&quot;</code></pre>
 </div>
 <p><br />
 </p>
@@ -696,7 +703,7 @@ <h2 id="saving-date-times-to-disk">Saving Date-Times to Disk</h2>
 <p><code>lubridate</code> makes this easy with
 <strong><code>format_ISO8601()</code></strong></p>
 <div class="sourceCode" id="cb26"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>lubridate<span class="sc">::</span><span class="fu">format_ISO8601</span>(<span class="fu">Sys.time</span>(), <span class="at">usetz =</span> <span class="cn">TRUE</span>)</span></code></pre></div>
-<pre><code>## [1] &quot;2023-10-30T09:47:55-0700&quot;</code></pre>
+<pre><code>## [1] &quot;2023-11-10T10:09:01-0800&quot;</code></pre>
 </div>
 </div>
 <p><br />