title: Interpolate between two columns of a Dataframe
body: <p>I am attempting to interpolate a value based on a number's position in a different column. Take this column for instance:</p>
  
  <pre><code>Coupon  Price
  9.5     109.04
  9.375   108.79
  9.25    108.54
  9.125   108.29
  9       108.04
  8.875   107.79
  8.75    107.54
  8.625   107.29
  8.5     107.04
  8.375   106.79
  8.25    106.54
  </code></pre>
  
  <p>Lets say I have a number like 107. I want to be able to find 107's relative distance from both 107.04 and 106.79 to interpolate the value that has the same relative distance between 8.5 and 8.375, the coupon values at the same index. Is this possible? I can solve this in excel using the FORECAST method, but want to know if it can be done in Python.</p>