title: Plotting a heatmap or colormap with interpolation in Python
body: <p>I need to create a 'heatmap' or 'colormap' in python. I have three python list, namely: X_COORDINATE, Z_COORDINATE and C_I. The X_COORDINATE and Z_COORDINATE lists contain the x and z coordinates that I have specific data points for (stored in the C_I list). The C_I list contains the values that I need to plot onto the x-z grid at the corresponding coordinates.</p>
  <p>The heatmap / colormap needs to interpolate between the points that are known and contained with the C_I list, such that the map is smooth, and NOT as square blocks. I cannot share the code or the source data as this is sensitive. However, for the purposes of understanding how to code one of these maps, assume that:</p>
  <pre><code>X = [1.1, 1.5, 2.0, 3.0, 4.0, 5.0, 1.1, 1.5, 2.0, 3.0, 4.0, 5.0, 1.1, 1.5, 2.0, 3.0, 4.0, 5.0, 0.0, 0.5, 1.0, 1.1, 1.5, 2.0, 3.0, 4.0, 5.0, 0.0, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0]
  
  Z = [0, 0, 0, 0, 0, 0, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 1, 1, 1, 1, 1, 1, 2.1, 2.1, 2.1, 2.1, 2.1, 2.1, 2.1, 2.1, 2.1, 2.5, 2.5, 2.5, 2.5, 2.5, 2.5, 2.5]
  
  C_I = [1.02414267447743, 0.210700871073941, 0.156586042435711, 0.109151033138569, 0.2279728779957, 0.204768257586954, 1.09037445301743, 0.287155868433615, 0.211257395413685, 0.132554129593619, 0.0900680495011601, 0.194608837248807, 1.34397119257655, 0.1201882143371, 0.17555070608144, 0.127220190160657, 0.204384526301353, 0.197414938747342, 0.195583977408476, 0.148150828086297, 0.183751866814816, 0.134858902076203, 0.183027629350907, 0.180267135381046, 0.0876356087026242, 0.183285092770786, 0.165502978081942, 0.0487725567447014, 0.172053559692846, 0.142204671797215, 0.166163224221791, 0.249334486033046, 0.150888488422605, 0.259452257883415]
  </code></pre>
  <p>So the zeroth element in the X_COORDINATE list is the x-coordinate for the first data point, the zeroth element in the Z_COORDINATE list is the z-coordinate for the first data point and the zeroth element in the C_I list is the value that must be plotted for that first point.</p>
  <p>I would like X_COORDINATE on the x-axis and Z_COORDINATE on the z-axis with the interior of the map coloured by the corresponding C_I values. To be clear I would like the map to be similar to the following attached images; although I would like the X and Z axes ticks to be present and the associated colorbar. How do I do this?</p>
  <p>The grid should be 5 units in the x-direction by 2.5 units in the z-direction (y-axis)</p>
  <p><img src="https://i.stack.imgur.com/oGakP.png" alt="sample heatmap" /></p>