title: Stop contourf interpolating values
body: <p>I am trying to plot some 2D values in a Basemap with contourf (matplotlib).</p>
  
  <p>However, contourf by default interpolates intermediate values and gives a smoother image of the data. </p>
  
  <p>Is there any way to make contourf to stop interpolating between values?</p>
  
  <p>I have tried by adding the keyword argument interpolation='nearest' but contourf does not use it. 
  Other option would be to use imshow, but there are some functionalities of contourf that do not work with imshow. </p>
  
  <p>I am using python 3.6.3 and matplotlib 2.1.2</p>