title: How to duplicate rows with incontinuous dates in R
body: <p>I need to duplicate rows with incontinuous dates to fill all the dates in a dataframe.</p>
  <p>Suppose this df:</p>
  <pre><code>df &lt;- data.frame(date = c(&quot;2022-07-05&quot;, &quot;2022-07-07&quot;, &quot;2022-07-11&quot;, &quot;2022-07-15&quot;, &quot;2022-07-18&quot;), letter = c(&quot;a&quot;, &quot;b&quot;, &quot;a&quot;, &quot;b&quot;, &quot;c&quot;))
  </code></pre>
  <p>The desired output is this df_new:</p>
  <pre><code>df_new &lt;- data.frame(date = c(&quot;2022-07-05&quot;, &quot;2022-07-06&quot;,
                            &quot;2022-07-07&quot;, &quot;2022-07-08&quot;, &quot;2022-07-09&quot;, &quot;2022-07-10&quot;,
                            &quot;2022-07-11&quot;, &quot;2022-07-12&quot;, &quot;2022-07-13&quot;, &quot;2022-07-14&quot;,
                            &quot;2022-07-15&quot;),
                   letter = c(&quot;a&quot;, &quot;a&quot;,
                              &quot;b&quot;, &quot;b&quot;, &quot;b&quot;, &quot;b&quot;,
                              &quot;a&quot;, &quot;a&quot;, &quot;a&quot;, &quot;a&quot;,
                              &quot;c&quot;))
  </code></pre>
  <p>Could you please help ?</p>