title: 'ImportError: No module named pytz' when trying to import pylab?
body: <p>As far as I can tell, I don't even need pytz for what I'm doing.</p>
  
  <p>I'm re-learning python for image processing using the O'Reilly book 'Programming Computer Vision with Python' for work (and I'm also new to mac, so on both counts I apologise if this is a stupid question). 
  Along with a 'empire.jpg' picture, I'm trying to run the script on page 16 which goes as follows:</p>
  
  <pre><code>from PIL import Image
  from pylab import *
  # read image to array
  im = array(Image.open('empire.jpg')) # plot the image
  imshow(im)
  # some points
  x = [100,100,400,400]
  y = [200,500,200,500]
  # plot the points with red star-markers
  plot(x,y,'r*')
  # line plot connecting the first two points
  plot(x[:2],y[:2])
  # add title and show the plot
  title('Plotting: "empire.jpg"')
  show()
  </code></pre>
  
  <p>but I get the following output with an error:</p>
  
  <pre><code>  File "plotch1.py", line 2, in &lt;module&gt;
      from pylab import *
    File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/pylab.py", line 1, in &lt;module&gt;
      from matplotlib.pylab import *
    File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/matplotlib/pylab.py", line 208, in &lt;module&gt;
      from matplotlib import mpl  # pulls in most modules
    File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/matplotlib/mpl.py", line 4, in &lt;module&gt;
      from matplotlib import axes
    File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/matplotlib/axes.py", line 18, in &lt;module&gt;
      from matplotlib import dates as mdates
    File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/matplotlib/dates.py", line 82, in &lt;module&gt;
      import pytz
  ImportError: No module named pytz
  </code></pre>
  
  <p>I'm using OS X 10.9.4.
  I've installed matplotlib and numpy from macpython.org and I've installed scipy 0.11.0 all for python 2.5. </p>
  
  <p>Do I even need pytz? If not, how can I get around this error?</p>