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POCreating grid and interpolating (x,y,z) for contour plot sagemath
 

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  1. POCreating grid and interpolating (x,y,z) for contour plot sagemath
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    <p>!I have values in the form of (x,y,z). By creating a list_plot3d plot i can clearly see that they are not quite evenly spaced. They usually form little "blobs" of 3 to 5 points on the xy plane. So for the interpolation and the final "contour" plot to be better, or should i say smoother(?), do i have to create a rectangular grid (like the squares on a chess board) so that the blobs of data are somehow "smoothed"? I understand that this might be trivial to some people but i am trying this for the first time and i am struggling a bit. I have been looking at the scipy packages like scipy.interplate.interp2d but the graphs produced at the end are really bad. Maybe a brief tutorial on 2d interpolation in sagemath for an amateur like me? Some advice? Thank you.</p> <p><strong>EDIT:</strong></p> <p><a href="https://docs.google.com/file/d/0Bxv8ab9PeMQVUFhBYWlldU9ib0E/edit?pli=1" rel="nofollow">https://docs.google.com/file/d/0Bxv8ab9PeMQVUFhBYWlldU9ib0E/edit?pli=1</a></p> <p>This is mostly the kind of graphs it produces along with this message:</p> <pre><code>Warning: No more knots can be added because the number of B-spline coefficients already exceeds the number of data points m. Probably causes: either s or m too small. (fp&gt;s) kx,ky=3,3 nx,ny=17,20 m=200 fp=4696.972223 s=0.000000 </code></pre> <p>To get this graph i just run this command:</p> <pre><code>f_interpolation = scipy.interpolate.interp2d(*zip(*matrix(C)),kind='cubic') plot_interpolation = contour_plot(lambda x,y: f_interpolation(x,y)[0], (22.419,22.439),(37.06,37.08) ,cmap='jet', contours=numpy.arange(0,1400,100), colorbar=True) plot_all = plot_interpolation plot_all.show(axes_labels=["m", "m"]) </code></pre> <p>Where matrix(c) can be a huge matrix like 10000 X 3 or even a lot more like 1000000 x 3. The problem of bad graphs persists even with fewer data like the picture i attached now where matrix(C) was only 200 x 3. That's why i begin to think that it could be that apart from a possible glitch with the program my approach to the use of this command might be totally wrong, hence the reason for me to ask for advice about using a grid and not just "throwing" my data into a command.</p>
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    1. COCan you post the plot, and describe what's wrong with it?
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      1. USuser545424
 

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