title: How to convert time (not date-time) variable into numeric?
body: <p>I have a data of swimming times that I would like to be able to plot over time. I was wondering if there was a quick way to change these variables from character to numeric? </p>
  
  <p>I started by trying to convert the times to a POSIX date-time format, but that proved to not be helpful, especially because I would like to do some ARIMA predictions on the data.</p>
  
  <p>Here is my data</p>
  
  <pre><code>times &lt;- c("47.45","47.69",  
             "47.69","47.82",  
             "47.84","47.92",  
             "47.96","48.13",  
             "48.16","48.16",  
             "48.16","48.31",  
             "49.01","49.27",  
             "49.33","49.40",  
             "49.48","49.51",  
             "52.85","52.89",  
             "53.14","54.31",  
             "54.63","56.91",  
             "1:18.39","1:20.26",
             "1:38.30")
  
  dates &lt;- c("2017-02-24 MST",
             "2017-02-24 MST",
             "2016-02-26 MST",
             "2018-02-23 MST",
             "2015-12-04 MST",
             "2015-03-06 MST",
             "2015-03-06 MST",
             "2016-12-02 MST",
             "2016-02-26 MST",
             "2017-11-17 MST",
             "2016-12-02 MST",
             "2017-11-17 MST",
             "2014-11-22 MST",
             "2017-01-13 MST",
             "2017-01-21 MST",
             "2015-10-17 MDT",
             "2017-01-27 MST",
             "2016-01-29 MST",
             "2017-10-20 MDT",
             "2016-11-05 MDT",
             "2015-11-07 MST",
             "2015-10-30 MDT",
             "2014-11-22 MST",
             "2016-11-11 MST",
             "2014-02-28 MST",
             "2014-02-28 MST",
             "2014-02-28 MST",)
  
  df &lt;- cbind(as.data.frame(dates),as.data.frame(times))
  </code></pre>
  
  <p>I hope to get a column for time, probably in seconds, so the first 24 obs would stay the same, but the last 3 obs would change to 78.39,80.26, and 98.30</p>