title: Controling xlim in plot
body: <p>My example : </p>
  
  <pre><code>x = c(1:15)
  y = c(-4:10)
  plot(x, y)
  </code></pre>
  
  <p>R gives <code>xlim</code> automatically as : <code>2, 4, 6, ..., 14</code></p>
  
  <p>How can I change it for : <code>1, 2, 3,..., 15</code></p>
  
  <p>I've tried : </p>
  
  <pre><code>my.limits = as.numeric(seq(1, 15, by = 1))
  x = c(1:15)
  y = c(-4:10)
  plot(x, y, ylim = c(-4,10), xlim = my.limits)
  </code></pre>
  
  <p>But with error : </p>
  
  <pre><code>Erreur dans plot.window(...) : valeur 'xlim' incorrecte
  </code></pre>