title: Discrete fourier transformation from a list of x-y points
body: <p>What I'm trying to do is, from a list of x-y points that has a periodic pattern, calculate the period. With my limited mathematics knowledge I know that Fourier Transformation can do this sort of thing.</p>
  
  <p>I'm writing Python code.</p>
  
  <p>I found a related answer <a href="https://stackoverflow.com/questions/24077913/discretized-continuous-fourier-transform-with-numpy">here</a>, but it uses an evenly-distributed x axis, i.e. <code>dt</code> is fixed, which isn't the case for me. Since I don't really understand the math behind it, I'm not sure if it would work properly in my code.</p>
  
  <p>My question is, does it work? Or, is there some method in <code>numpy</code> that already does my work? Or, how can I do it?</p>
  
  <p><strong>EDIT:</strong> All values are Pythonic <code>float</code> (i.e. double-precision)</p>