title: Create new vector based on conditions from another vector
body: <p>I have a vector <code>v1 = c(0, 3, 5, 1, 1, 1, 3, 5, 0)</code>. How can I create a vector of equal length BUT with values -1 if 0 or 3 and 1 if 1 or 5.</p>
  
  <p>So with <code>v1 = c(0, 3, 5, 1, 1, 3, 5, 0)</code>, I am expecting a new vector:</p>
  
  <p><code>v2 = c(-1, -1, 1, 1, 1, -1, 1, -1)</code></p>