title: Fill a vector in Julia with a repeated list
body: <p>I would like to create a column vector X by repeating a smaller column vector G of length h a number n of times. The final vector X will be of length h*n. For example</p>
  
  <pre><code>G = [1;2;3;4] #column vector of length h
  X = [1;2;3;4;1;2;3;4;1;2;3;4] #ie X = [G;G;G;G] column vector of
  length h*n
  </code></pre>
  
  <p>I can do this in a loop but is there an equivalent to the 'fill' function that can be used without the dimensions going wrong. When I try to use fill for this case, instead of getting one column vector of length h*n I get a column vector of length n where each row is another vector of length h. For example I get the following:</p>
  
  <pre><code>X = [[1,2,3,4];[1,2,3,4];[1,2,3,4];[1,2,3,4]]
  </code></pre>
  
  <p>This doesn't make sense to me as I know that the ; symbol is used to show elements in a row and the space is used to show elements in a column. Why is there the , symbol used here and what does it even mean? I can access the first row of the final output X by X[1] and then any element of this by X[1][1] for example. </p>
  
  <p>Either I would like to use some 'fill' equivalent or some sort of 'flatten' function if it exists, to flatten all the elements of the X into one column vector with each entry being a single number.</p>
  
  <p>I have also tried the reshape function on the output but I can't get this to work either.</p>