Re: [Matplotlib-users] for a log y axis, set_major_formatter then twiny() removes the set_major_formatter

[Eric F. <ef...@ha...>]

On 2012/08/19 10:31 AM, Christopher Graves wrote:
> Hi
>
>
> I do not think this is the expected behavior. First, run the following:
>
>
> from pylab import *
>
> plot([0,3],[0.2,0.7])
>
> ax1 = gca()
>
> ax1.set_yscale('log')
>
> gca().yaxis.set_major_formatter(FormatStrFormatter('$%g$'))
>
> #ax2 = ax1.twiny()
>
> #ax2.set_xlim(ax1.get_xlim())
>
> show()
>
>
> You will see that the y-axis is log10rithmic and axis labels are 0.1 and
> 1 rather than 10^-1 and 10^0, due to the use of set_major_formatter().
>
>
> Now uncomment the 2 commented lines and run it again. It seems that upon
> applying a twiny(), the set_major_formatter() action is removed and the
> y-axis is now displayed as 10^-1 and 10^0. Or more likely, the y-axis is
> "overwritten" with a new y-axis present in ax2. One can add another
> gca().yaxis.set_major_formatter(FormatStrFormatter('$%g$')) before the
> show() and it works as intended. However, it seems like unexpected
> behavior to "lose" the formatting when twinning the axis to add a
> secondary x-axis. Any advice or agreement that this could be a bug?

Yes, I think this is a bug.

Eric

>
>
> Best,
>
> Chris
>