title: Arbitrary image slice with python/numpy
body: <p>I would like to plot a 1D profile of a 2D image along an arbitrary line. The code below loads the image data hosted on github and plots it:</p>
  
  <pre><code>import urllib
  import numpy as np
  import matplotlib.pyplot as plt
  
  url = "https://gist.github.com/andreiberceanu/7141843/raw/0b9d50d3d417b1cbe651560470c098700df5a1fc/image.dat"
  f = urllib.urlopen(url)
  data = np.loadtxt(f)
  
  plt.imshow(data)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/WJV8k.png" alt="waves with line"></p>
  
  <p>The red line in the plot above was drawn by hand, as an example. I suppose one can parametrize it in the form a*x + b. I am also guessing some sort of interpolation is necessary, because the line passes though points which may not be part of the original 2D array of data.</p>