[Matplotlib-users] log xaxis for contourf

[Jody Klymak]

You are giving contour very irregularly spaced data in x.  Its trying to come up w/ those last few contours with very little data and I guess its misbehaving.

If it were me, I’d interpolate onto a regular log10 grid first and then send to contour.  Then you have control over how the interpolation takes place...

You may also want to consider just using pcolormesh.  

Cheers,  Jody

> On Nov 23, 2017, at  18:42 PM, dimitrif <df388 at cam.ac.uk> wrote:
> 
> Hi to all,
> 
> I spent about 3 hours trying to fix a plotting problem I have with
> matplotlib.pyplot...unfortunately without any sucess.
> 
> I want to have a logarithmic xaxis in my contourf plot. Since this is not
> directly possible, I took the log10 of the axis and simply used them. Doing
> so, I get some white space inside the plot for some reason. Can someone give
> me a hint why this is happening? I use the following fraction of code:
> 
> #without log scale
> plt.figure(11), plt.cla()
> cf1 = plt.contourf(f_psd_welch, traverseCoord,
> 10*np.log10(psd_hotwire_FS_welch),cmap='viridis')
> cbar1 = plt.colorbar(cf1)
> plt.xlim([min(f_psd_welch), max(f_psd_welch)]), plt.ylim([-50, 50])
> 
> <http://matplotlib.1069221.n5.nabble.com/file/t5112/normalX.png> 
> 
> #with logscale
> plt.figure(11), plt.cla()
> cf1 = plt.contourf(np.log10(f_psd_welch), traverseCoord,
> 10*np.log10(psd_hotwire_FS_welch),cmap='viridis')
> cbar1 = plt.colorbar(cf1)
> plt.xlim([min(np.log10(f_psd_welch[1:])), max(np.log10(f_psd_welch[1:]))]),
> plt.ylim([-50, 50])
> 
> <http://matplotlib.1069221.n5.nabble.com/file/t5112/logX.png> 
> 
> The output is attached.
> I would be happy about any help!
> 
> Thanks,
> Dimitri
> 
> 
> 
> --
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