title: Converting dataframe with multiple values for one date into a ts object in R
body: <p>I have a large dataset with multiple values for specific days. There are missing values in the dataset as it's for a long period of time. Here's a small example: </p>
  
  <pre><code>set.seed(1)
  data &lt;- data.frame(
   Date = sample(c("1993-07-09", "1993-07-09", "1993-07-10", "1993-08-11", "1993-08-11", "1993-08-11")),
   Oxygen = sample(c(0.2, 0.4, 0.4, 0.2, 0.4, 0.5))
  )
  data$Date &lt;- as.Date(data$Date)
  </code></pre>
  
  <p>I want to convert this dataframe into a <strong>ts object</strong>, so that I can forecast, use arima models, and eventually find outliers. </p>
  
  <p>It specifically needs to be a ts object and not a xts object.</p>
  
  <p>The problem I'm facing is:
  1) I don't know how to convert a data frame into a ts object.
  2) Create a ts object that allows for multiple values to take place for a single day.</p>
  
  <p>Any help would be greatly appreciated. Thank you! </p>