title: Discrete heat map with GNUPLOT
body: <p>I'm trying to make something as a heat map with GNUPLOT but I need that my palette takes discrete colors for defined values.</p>
  
  <p>I mean, my data file has three columns, for example:</p>
  
  <p>x    y     value</p>
  
  <hr>
  
  <p>0.0    0.0    10<br>
  0.0    0.5    2<br>
  0.0    1.0    2<br>
  0.5    1.0    10<br>
  1.0    0.0    -1<br>
  1.0    1.0    -1</p>
  
  <p>I need that each point has one color depending of its value. Traditional heat map mixes point making regions of continuos colors, but I need it in a discrete form.</p>