title: Pasting two vectors with combinations of all vectors' elements
body: <p>I have two vectors: </p>
  
  <pre><code>vars &lt;- c("SR", "PL")
  vis &lt;- c(1,2,3)
  </code></pre>
  
  <p>Based on these vectors I would like to create the following vector: </p>
  
  <pre><code>"SR.1"  "SR.2"  "SR.3"  "PL.1"  "PL.2"  "PL.3"
  </code></pre>
  
  <p>With <code>paste</code> I have the following result: </p>
  
  <pre><code>paste(vars, vis, sep=".")
   [1] "SR.1" "PL.2" "SR.3"
  </code></pre>
  
  <p>How can I create the vector I need?</p>