title: Duplicate rows while creating sequence of rows
body: <p>I am trying to creating sequence of rows like below:</p>
  
  <pre><code>time_index &lt;-seq(from = as.POSIXct("2019-10-21 06:00:00",tz = "US/Eastern"), 
                   to = as.POSIXct("2019-12-31 00:00:00",tz = "US/Eastern"), by = "hour")
  
  constraint_matrix&lt;-data.frame(row.names = time_index)
  </code></pre>
  
  <p>But it is showing below error:</p>
  
  <blockquote>
  <pre><code>Error in data.frame(row.names = row) : 
     duplicate row.names: 2019-11-03 01:00:00
  </code></pre>
  </blockquote>