title: Array interpolation in python?
body: <p>I have two arrays :</p>
  
  <pre><code>array_x = [x1, x2, x3, x4... xn]
  array_y = [y1, y2, y3, y4... yn]
  </code></pre>
  
  <p>I would like to have a function <code>f(array_x, array_y, value_x)</code> that returns the <code>value_y</code> associated to the <code>value_x</code> by interpolation into the arrays. </p>
  
  <p>How to do that ?</p>