title: Adding noise to numpy array
body: <p>So say I'm trying to create a 100-sample dataset that follows a certain line, maybe 2x+2.  And I want the values on my X-axis to range from 0-1000.  To do this, I use the following.</p>
  
  <pre><code>X = np.random.random(100,1) * 1000
  Y = (2*X) + 2
  data = np.hstack(X,Y)
  </code></pre>
  
  <p>The hstack gives me the array with corresponding x and y values.  That part works.  But if I want to inject noise into it in order to scatter the datapoints further away from that 2x+2 line...that's what I can't figure out.  </p>
  
  <p>Say for example, I want that Y array to have a standard deviation of 20.  How would I inject that noise into the y values?</p>