title: How to convert a list column to a vector in a tibble in R
body: <p>I am trying to collapse the Weeks column in the tibble (called data) below so that the result is a tibble with two columns: 1 for weeks and another for associated values. Since the weeks column is a list, I am not sure how to do it. Could you please help?</p>
  
  <pre><code>&gt; head(data)
  # A tibble: 6 x 1
    ``$Weeks   $Value
    &lt;list&gt;      &lt;dbl&gt;
  1 &lt;date [9]&gt;     30
  2 &lt;date [3]&gt;     20
  3 &lt;date [3]&gt;     15
  4 &lt;date [5]&gt;     10
  5 &lt;date [2]&gt;      9
  6 &lt;date [9]&gt;      5
  </code></pre>
  
  <p>desired result would look like:</p>
  
  <pre><code>      $Weeks   $Value
        &lt;Date&gt;      &lt;dbl&gt;
   1  "2019-01-01     30
   2  "2019-01-08     30
   3  "2019-01-15     30
   etc..
  </code></pre>
  
  <p>Current Structure:</p>
  
  <pre><code>  &gt; str(data)
  List of 1
   $ :Classes ‘tbl_df’, ‘tbl’ and 'data.frame':   7 obs. of  2 variables:
    ..$ Weeks:List of 7
    .. ..$ : Date[1:9], format: "2018-11-11" "2018-11-18" "2018-11-25" "2018-12-02" ...
    .. ..$ : Date[1:3], format: "2018-12-02" "2018-12-09" "2018-12-16"
    .. ..$ : Date[1:3], format: "2018-12-23" "2018-12-30" "2019-01-06"
    .. ..$ : Date[1:5], format: "2018-11-04" "2018-11-11" "2018-11-18" "2018-11-25" ...
    .. ..$ : Date[1:2], format: "2018-11-25" "2018-12-02"
    .. ..$ : Date[1:9], format: "2018-11-18" "2018-11-25" "2018-12-02" "2018-12-09" ...
    .. ..$ : Date[1:14], format: "2018-09-30" "2018-10-07" "2018-10-14" "2018-10-21" ...
    ..$ Value: num [1:7] 30 20 15 10 9 5 6
  </code></pre>
  
  <p>dput(data)</p>
  
  <pre><code>&gt; dput(data)
  list(structure(list(Weeks = list(structure(c(17846, 17853, 17860, 
  17867, 17874, 17881, 17888, 17895, 17902), class = "Date"), structure(c(17867, 
  17874, 17881), class = "Date"), structure(c(17888, 17895, 17902
  ), class = "Date"), structure(c(17839, 17846, 17853, 17860, 17867
  ), class = "Date"), structure(c(17860, 17867), class = "Date"), 
      structure(c(17853, 17860, 17867, 17874, 17881, 17888, 17895, 
      17902, 17909), class = "Date"), structure(c(17804, 17811, 
      17818, 17825, 17832, 17839, 17846, 17853, 17860, 17867, 17874, 
      17881, 17888, 17895), class = "Date")), Value = c(30, 20, 
  15, 10, 9, 5, 6)), row.names = c(NA, -7L), class = c("tbl_df", 
  "tbl", "data.frame")))
  </code></pre>