title: How to get transparency into pcolormesh in JuliaLang?
body: <p>I'm using PyPlot on Julia.
  I'm using pcolormesh and would like certain values to be transparent, so that you can see the pcolormesh plot that is behind.</p>
  
  <p>In python you could do this with Masked arrays but, how can I accomplish it with Julia?</p>
  
  <pre><code>figure()
  p = pcolormesh(XLAT[1,ind1:ind2],1:31,squeeze(Div[hora,:,1,ind1:ind2],(1,3)),vmin=min1,vmax=max1,shading="gouraud",cmap="Spectral")
  p2 = pcolormesh(XLAT[1,ind1:ind2],1:31,a,vmin=0, vmax=2,shading="gouraud",cmap="YlOrBr")
  draw()
  </code></pre>
  
  <p>p2 is an array with just values '2' and 'NaN'; and I would want that one of those values is transparent and the other has a color.</p>
  
  <p>how would you do it?</p>
  
  <p>Very thanks!</p>