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

[Damon M. <dam...@gm...>]

On Mon, Aug 20, 2012 at 09:13:10AM -0400, Michael Droettboom wrote:
> I've filed an issue for this here:
> 
> https://github.com/matplotlib/matplotlib/issues/1110
>

I think I have sussed out what's going on here.

See PR: https://github.com/matplotlib/matplotlib/pull/1145

Basically, on creating a new Axes object, if a shared axes was passed
in, a copy of the current axes scale is executed. This overwrites the
current formatter.

> 
> Mike
> 
> On 08/19/2012 05:55 PM, Eric Firing wrote:
> >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
> >>
> >
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-- 
Damon McDougall
http://www.damon-is-a-geek.com
B2.39
Mathematics Institute
University of Warwick
Coventry
West Midlands
CV4 7AL
United Kingdom