>>> """
==============
Triinterp Demo
==============

Interpolation from triangular grid to quad grid.
"""
... import matplotlib.pyplot as plt
... import matplotlib.tri as mtri
... import numpy as np
... 
... # Create triangulation.
... x = np.asarray([0, 1, 2, 3, 0.5, 1.5, 2.5, 1, 2, 1.5])
... y = np.asarray([0, 0, 0, 0, 1.0, 1.0, 1.0, 2, 2, 3.0])
... triangles = [[0, 1, 4], [1, 2, 5], [2, 3, 6], [1, 5, 4], [2, 6, 5], [4, 5, 7],
...              [5, 6, 8], [5, 8, 7], [7, 8, 9]]
... triang = mtri.Triangulation(x, y, triangles)
... 
... # Interpolate to regularly-spaced quad grid.
... z = np.cos(1.5 * x) * np.cos(1.5 * y)
... xi, yi = np.meshgrid(np.linspace(0, 3, 20), np.linspace(0, 3, 20))
... 
... interp_lin = mtri.LinearTriInterpolator(triang, z)
... zi_lin = interp_lin(xi, yi)
... 
... interp_cubic_geom = mtri.CubicTriInterpolator(triang, z, kind='geom')
... zi_cubic_geom = interp_cubic_geom(xi, yi)
... 
... interp_cubic_min_E = mtri.CubicTriInterpolator(triang, z, kind='min_E')
... zi_cubic_min_E = interp_cubic_min_E(xi, yi)
... 
... # Set up the figure
... fig, axs = plt.subplots(nrows=2, ncols=2)
... axs = axs.flatten()
... 
... # Plot the triangulation.
... axs[0].tricontourf(triang, z)
... axs[0].triplot(triang, 'ko-')
... axs[0].set_title('Triangular grid')
... 
... # Plot linear interpolation to quad grid.
... axs[1].contourf(xi, yi, zi_lin)
... axs[1].plot(xi, yi, 'k-', lw=0.5, alpha=0.5)
... axs[1].plot(xi.T, yi.T, 'k-', lw=0.5, alpha=0.5)
... axs[1].set_title("Linear interpolation")
... 
... # Plot cubic interpolation to quad grid, kind=geom
... axs[2].contourf(xi, yi, zi_cubic_geom)
... axs[2].plot(xi, yi, 'k-', lw=0.5, alpha=0.5)
... axs[2].plot(xi.T, yi.T, 'k-', lw=0.5, alpha=0.5)
... axs[2].set_title("Cubic interpolation,\nkind='geom'")
... 
... # Plot cubic interpolation to quad grid, kind=min_E
... axs[3].contourf(xi, yi, zi_cubic_min_E)
... axs[3].plot(xi, yi, 'k-', lw=0.5, alpha=0.5)
... axs[3].plot(xi.T, yi.T, 'k-', lw=0.5, alpha=0.5)
... axs[3].set_title("Cubic interpolation,\nkind='min_E'")
... 
... fig.tight_layout()
... plt.show()
... 
... #############################################################################
... #
... # .. admonition:: References
... #
... #    The use of the following functions, methods, classes and modules is shown
... #    in this example:
... #
... #    - `matplotlib.axes.Axes.tricontourf` / `matplotlib.pyplot.tricontourf`
... #    - `matplotlib.axes.Axes.triplot` / `matplotlib.pyplot.triplot`
... #    - `matplotlib.axes.Axes.contourf` / `matplotlib.pyplot.contourf`
... #    - `matplotlib.axes.Axes.plot` / `matplotlib.pyplot.plot`
... #    - `matplotlib.tri`
... #    - `matplotlib.tri.LinearTriInterpolator`
... #    - `matplotlib.tri.CubicTriInterpolator`
... #    - `matplotlib.tri.Triangulation`
...