Re: [matplotlib-devel] Completely wrong tick formatting

[Pål G. E. <pa...@gm...>]

Hi

Thank you that solves the problem we had.
I'm sorry for posting this on the development list, it was intended for the
users list, and I somehow entered the wrong address.

Regards

Pål

On 7 July 2013 21:44, Eric Firing <ef...@ha...> wrote:

> On 2013/07/04 11:43 PM, Pål Gunnar Ellingsen wrote:
> > Hi
> >
> > I'm having some problems with the formatter of ticks in a polar plot.
> > Below is a minimum example
> > The first figure is correct, the second has wrong ticks.
> >
> > This has be tested both on 1.2.0 and the latest from git (1.4.x, commit
> > 64cc3416396ffb2811af80fc810ed63572df71d9 )
> >
> > Does anyone know whys this happens?
> > Is it a bug in MaxNLocator
>
> No, it is a misunderstanding of how the colorbar works.  It's long axis
> is using its own units, and it maps the color scale to those units.
> Therefore, one should not try to manipulate the axis properties
> directly.  Below I show two altered lines and one deletion.  I think
> this will produce what you want.
>
> >
> > Kind regards
> >
> > Pål
> >
> > ---------------------------
> > #!/usr/bin/env python
> >
> > import numpy as np
> > import matplotlib.pyplot as plt
> > from matplotlib.ticker import MaxNLocator
> >
> > # Data
> > M=np.sin(np.meshgrid(np.arange(30),np.arange(30)))
> > M=np.squeeze(M[0,:,:])
> > Radius=np.arange(30)
> > Theta=np.arange(30)
> >
> > # Plotting the correct figure
> > print('Correct ticks')
> > fig=plt.figure()
> > ax1 = fig.add_axes([0,0,0.8,1],projection='polar')
> > c = ax1.pcolormesh(Theta, Radius, M)
> > ax1.set_frame_on(False)
> > plt.xticks([])
> > plt.yticks([])
> > ax2=fig.add_axes([0.9,0.1,0.05,0.7])
> > cb=fig.colorbar(c,cax=ax2)
> > plt.show()
> >
> > # Doing the same plot
> > print('Wrong ticks by using formatter')
> > fig=plt.figure()
> > ax1 = fig.add_axes([0,0,0.8,1],projection='polar')
> #> c = ax1.pcolormesh(Theta, Radius, M)
>
> c = ax1.pcolormesh(Theta, Radius, M, vmin=-1, vmax=1)
>
> > ax1.set_frame_on(False)
> > plt.xticks([])
> > plt.yticks([])
> > ax2=fig.add_axes([0.9,0.1,0.05,0.7])
> #> cb=fig.colorbar(c,cax=ax2)
>
> cb = fig.colorbar(c, cax=ax2, ticks=MaxNLocator(3))
>
> >
> #> # except now setting a limit to the number of ticks using a formatter
> #> # which results in wrong ticks
> #> cb.ax.yaxis.set_major_locator(MaxNLocator(3))
>
> > plt.show()
>
> Eric
>
> > -----------------------
> >
> >
> >
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