title: Replacing Nones in a python array with zeroes
body: <p>I've just joined two arrays of unequal length together with the command:</p>
  
  <pre><code>allorders = map(None,todayorders, lastyearorders)
  </code></pre>
  
  <p>where "none" is given where today orders fails to have a value (as the todayorders array is not as long).</p>
  
  <p>However, when I try to pass the allorders array into a matplotlib bar chart:</p>
  
  <pre><code> p10= plt.bar(ind, allorders[9],   width, color='#0000DD', bottom=allorders[8])
  </code></pre>
  
  <p>..I get the following error:</p>
  
  <pre><code>TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'
  </code></pre>
  
  <p>So, is there a way for matplotlib to accept none datatypes? if not, how do I replace the 'Nones' with zeroes in my allorders array?</p>
  
  <p>If you can, as I am a Python newbie (coming over from the R community), please provide detailed code from start to finish that I can use/test.</p>