title: R prevent repeated items while using paste() for vectors
body: <p>Consider the following:</p>
  
  <pre><code>a = 1:10
  paste("The list is:", a)
  </code></pre>
  
  <p>And the result would be:</p>
  
  <pre><code> [1] "The list is: 1"  "The list is: 2"  "The list is: 3"  "The list is: 4" 
   [5] "The list is: 5"  "The list is: 6"  "The list is: 7"  "The list is: 8" 
   [9] "The list is: 9"  "The list is: 10"
  </code></pre>
  
  <p>I have solved it by:</p>
  
  <pre><code>paste("The list is:", paste(a, collapse=", "))
  # "The list is: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10"
  </code></pre>
  
  <p>Is there any better idea?</p>