title: Changing Dates as per production shift timings in R
body: <p>i want to change the date of the data entry based on timestamp. Basically, the company starts its operations at 7:00am in morning and works till 6:59am next day. this entire duration is counted as 1 day.
  So basically 19th Nov 2020 would mean starting 19-11-2020 07:00 to 20-11-2020 06:59</p>
  <p>i have this dataset</p>
  <pre><code>structure(list(Timestamp = structure(c(1593714765.03054, 1593714824.99918, 
  1593714884.96776, 1593714945.01468, 1593715005.01454, 1593715064.98314, 
  1593715125.03002, 1593715185.18608, 1593715244.99822, 1593715304.96657
  ), class = c(&quot;POSIXct&quot;, &quot;POSIXt&quot;), tzone = &quot;Asia/Kolkata&quot;), Date = structure(c(18446, 
  18446, 18446, 18446, 18446, 18446, 18446, 18446, 18446, 18446
  ), class = &quot;Date&quot;), Time = c(&quot;00:02&quot;, &quot;00:03&quot;, &quot;00:04&quot;, &quot;00:05&quot;, 
  &quot;00:06&quot;, &quot;00:07&quot;, &quot;00:08&quot;, &quot;00:09&quot;, &quot;00:10&quot;, &quot;00:11&quot;), `HCM 18` = c(7, 
  8, 7, 8, 7, 7, 8, 7, 8, 7), `HCM 19` = c(8, 8, 8, 8, 8, 7, 8, 
  8, 8, 8), `HCM 20` = c(7, 7, 7, 7, 8, 7, 4, 8, 7, 7), `HCM 21` = c(8, 
  7, 8, 8, 8, 7, 8, 8, 8, 8), `HCM 22` = c(8, 7, 8, 7, 7, 8, 7, 
  8, 7, 7), `HCM 23` = c(8, 7, 8, 8, 8, 7, 8, 8, 8, 8), `HCM 24` = c(7, 
  7, 7, 6, 7, 7, 7, 6, 4, 0), `HCM 25` = c(8, 8, 8, 7, 8, 8, 8, 
  7, 8, 8), `HCM 54` = c(7, 8, 8, 7, 6, 8, 7, 8, 8, 7), `HCM 55` = c(8, 
  7, 8, 7, 8, 8, 7, 8, 8, 7), `HCM 56` = c(8, 8, 8, 7, 8, 8, 7, 
  8, 8, 7), `HCM 57` = c(8, 8, 7, 8, 8, 7, 8, 8, 7, 8), `HCM 58` = c(8, 
  8, 7, 8, 7, 8, 7, 8, 7, 8), `HCM 59` = c(8, 1, 6, 8, 8, 7, 8, 
  8, 7, 8), `HCM 60` = c(8, 7, 8, 8, 7, 8, 8, 7, 8, 8)), row.names = c(NA, 
  10L), class = &quot;data.frame&quot;)
  </code></pre>
  <p>So now i need to change the date for time less than 7:00am to previous day.</p>
  <p>i want to do this in R.</p>