title: Get Lent from timeDate in R
body: <p>I would like to get all Lent Fridays from 2010 to 2020. I am currently using <code>timeDate</code> to get holidays such as Easter, Good Friday, and Ash Wednesday. As follows</p>
  
  <pre><code>aw &lt;- as.Date(AshWednesday(year = 2010:2020))
  gf &lt;- as.Date(GoodFriday(year = 2010:2020))
  </code></pre>
  
  <p>I can also get fixed holidays that don't come with the package. For example</p>
  
  <pre><code>mg &lt;- as.Date(AshWednesday(year = 2010:2020)-1) #Mardi Gras
  cm &lt;- as.Date(seq(ymd('2010-05-05'),ymd('2020-05-05'), by = '1 year')) #cinco de mayo
  </code></pre>
  
  <p>But I am struggling to get all Lent Fridays per year.</p>
  
  <p>Note: Lent begins on the Sunday that follows Ash Wednesday and lasts for 40 days.</p>
  
  <p>As posted below, the following code worked:</p>
  
  <pre><code>library(dplyr)
  library(purrr)
  library(tidyr)
  library(lubridate)
  
  tibble(aw) %&gt;% 
      mutate(aw_sunday = aw + lubridate::days(0)) %&gt;%  #Find the first Sunday after each Ash Wednesday
      mutate(extra_days = map(aw_sunday, function(x) x + lubridate::days(1:40))) %&gt;% #Find all series of 40 days after each sunday
      unnest %&gt;% 
      mutate(week_day = lubridate::wday(extra_days, label = TRUE)) %&gt;% #Find all the day names
      filter(week_day == 'Fri') %&gt;%  # Filter out the fridays
      pull(extra_days)
  </code></pre>
  
  <p>I changed <code>days(4)</code> to <code>days(0)</code> because I think lent Fridays actually start immediately after Ash Wednesday, not skipping a week. I pulled the Note above from Wikipedia under "the Ambrosian Rite". I guess there is a difference.</p>