Very cool: includes natural neighbor interpolation in N dimensions! ---------- Forwarded message ---------- From: Pauli Virtanen <pav@iki.fi> Date: Tue, Aug 31, 2010 at 3:01 PM Subject: [SciPy-Dev] RFR: N-dimensional interpolation To: scipy-dev@scipy.org Sun, 25 Jul 2010 15:35:11 +0000, Pauli Virtanen wrote:

I took the Qhull by the horns, and wrote a straightforward `griddata` implementation for working in N-D: [clip]

It's now committed to SVN (as it works-well-for-me). Post-mortem review and testing is welcome. http://projects.scipy.org/scipy/changeset/6653 http://projects.scipy.org/scipy/changeset/6655 http://projects.scipy.org/scipy/changeset/6657 What's in there is: 1) scipy.spatial.qhull   Delaunay decomposition and some associated low-level N-d geometry   routines. 2) scipy.interpolate.interpnd   N-dimensional interpolation:   1) Linear barycentric interpolation   2) Cubic spline interpolation (2D-only, C1 continuous,      approximately minimum-curvature). 3) scipy.interpolate.griddatand   Convenience interface to the N-d interpolation classes. What could be added: - More comprehensive interface to other features of Qhull - Using qhull_restore, qhull_save to store Qhull contexts  instead of copying the relevant data? - Optimizing the cubic interpolant - Monotonic cubic interpolation - Cubic interpolation in 3-d - Natural neighbour interpolation - etc.    *** Example: import numpy as np def func(x, y):    return x*(1-x)*np.cos(4*np.pi*x) * np.sin(4*np.pi*y**2)**2 grid_x, grid_y = np.mgrid[0:1:100j, 0:1:200j] points = np.random.rand(1000, 2) values = func(points[:,0], points[:,1]) from scipy.interpolate import griddata grid_z0 = griddata(points, values, (grid_x, grid_y), method='nearest') grid_z1 = griddata(points, values, (grid_x, grid_y), method='linear') grid_z2 = griddata(points, values, (grid_x, grid_y), method='cubic') import matplotlib.pyplot as plt plt.subplot(221) plt.imshow(func(grid_x, grid_y).T, extent=(0,1,0,1), origin='lower') plt.plot(points[:,0], points[:,1], 'k.', ms=1) plt.title('Original') plt.subplot(222) plt.imshow(grid_z0.T, extent=(0,1,0,1), origin='lower') plt.title('Nearest') plt.subplot(223) plt.imshow(grid_z1.T, extent=(0,1,0,1), origin='lower') plt.title('Linear') plt.subplot(224) plt.imshow(grid_z2.T, extent=(0,1,0,1), origin='lower') plt.title('Cubic') plt.gcf().set_size_inches(6, 6) plt.show() -- Pauli Virtanen _______________________________________________ SciPy-Dev mailing list SciPy-Dev@scipy.org http://mail.scipy.org/mailman/listinfo/scipy-dev