title: Convert HH:MM:SS column to ZT time
body: <p>I am hoping somebody can help me with a logic question in R-studio. I have a rather large data set, with &quot;Time&quot; as one of my columns. This column has values from 00:00:00 to 23:59:00, and is in HH:MM:SS format.</p>
  <p>Because of some trouble I have had with analysis of time in this format, I am trying to create a new column, called &quot;ZT&quot; where I convert this time column to ZT time. Lights turn on at 7am, so need the time 07:00:00 to correspond to ZT=0, with 07:01:00 to correspond to ZT=0.016... and so on and so forth.</p>
  <p>Can anybody help me with this? It would be much appreciated!</p>