title: Is it possible to merge two time series in one?
body: <p>I've been trying to merge two ts objects, the second one starts exactly one period after the next one.
  For example, take the following two time series</p>
  
  <pre><code>ts1&lt;-ts(c(1:12),star=c(2014,1),freq=12)
  ts2&lt;-ts(c(13:24),star=c(2015,1),freq=12)
  </code></pre>
  
  <p>As you can see, both of them match perfectly in order to make a single ts out of this two ts objects. I thought the logical answer would be the rbind() function. But it makes a matrix out of them, as follows...</p>
  
  <pre><code>&gt; rbind(ts1,ts2)
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
  ts1    1    2    3    4    5    6    7    8    9    10    11    12
  ts2   13   14   15   16   17   18   19   20   21    22    23    24
  </code></pre>
  
  <p>I've tried without success other functions like merge,cbind. Using c() I've managed to get one only timeseries, the main problema is that I lose structure attributes of the original timeseries, this is bad because I'm trying to use the function forecast with the new ts but it gives me  this:</p>
  
  <pre><code>Error: variables ... were specified with different types from the fit
  </code></pre>
  
  <p>I would be happy just with being able to add additional observations to a time series. Something like adding the value 13 to ts1 for January,2015 but I haven´t found how to do this either.</p>
  
  <p>I think is funny because I see this as a perfectly natural thing to ask for to a ts object, but I haven´t found any other question that helps me out here. Well let´s hope this is not a too silly question.</p>