title: combining arrays
body: <p>I have three separate 1d arrays of a list of numbers, their squares and cubes (created by a 'for' loop). 
  I would like these arrays to appear in three corresponding columns, however I have tried the column_stack function and python says its not defined. I have read about the vstack and hstack functions but am confused about which to use and what exactly they do. 
  My code so far reads;</p>
  
  <pre><code>import numpy
  makearange = lambda a: numpy.arange(int(a[0]),int(a[1]),int(a[2]))
  x = makearange(raw_input('Enter start,stop,increment: ').split(','))
  y = numpy.zeros(len(x), dtype=int)
  z = numpy.zeros(len(x), dtype=int)
  for i in range(len(x)):
      y[i] = x[i]**2
  for i in range(len(x)):
      z[i] = x[i]**3
  print 'original array: ',x
  print 'squared array: ',y
  print 'cubed array: ', z
  </code></pre>
  
  <p>I would appreciate any advice</p>