title: NP.FFT on python list
body: <p>Could you please advise me on the following:
  I gather data from an Arduino ADC and store the data in a list on a Raspberry Pi 4 with Python 3.
  The list is called 'dataList' and contains 1024 10 bits samples. This all works fine: I can reproduce the sampled signal on the Raspberry.</p>
  
  <p>I would like to use the power spectrum of the acquired signal using numpy FFT.
  I tried the following:</p>
  
  <p>[see below]</p>
  
  <p>This should illustrate what I'm trying to do; however this produces incoherent output. The sampled signal has a frequency of about 300 Hz. I would be very grateful for any hints in the right direction!</p>
  
  <pre><code>def show_FFT(window):
     fft = np.fft.fft (dataList, 1024, -1, None)
     for X_value in range (0,512, 1):
         Y_value = fft ([X_value]
         gfxdraw.pixel (window, X_value, int(abs(Y_value), black)
  </code></pre>