title: Assign value to a slice of a numpy array
body: <p>I want to get slices from a numpy array and assign them to a larger array.
  The slices should be 64 long and should be taken out evenly from the source array.
  I tried the following:</p>
  
  <pre><code>r = np.arange(0,magnitude.shape[0],step) 
  magnitudes[counter:counter+len(r),ch] = magnitude[r:r+64]
  </code></pre>
  
  <p>I get the following error when I tried the above code:</p>
  
  <pre><code>TypeError: only integer arrays with one element can be converted to an index
  </code></pre>
  
  <p>What is the most pythonic way to achieve the slicing?</p>