title: Python: Make Copy of List
body: <p>How do I make a copy of a list, so I can edit the copy without affecting the original.  Ex:</p>
  
  <pre><code>x = [1., 2., 3., 4.]
  y = x
  y[0] = 9.
  </code></pre>
  
  <p>The output is:</p>
  
  <pre><code>x: [9.0, 2.0, 3.0, 4.0] 
  y: [9.0, 2.0, 3.0, 4.0] 
  </code></pre>
  
  <p>when I want x to be:</p>
  
  <pre><code>x: [1.0, 2.0, 3.0, 4.0]
  </code></pre>
  
  <p>So how do I make a copy of a variable while keeping the original unchanged?</p>
  
  <p>Thanks in advance,</p>
  
  <p>Eric</p>