Re: [Matplotlib-users] synchronization of ticks position in twinx plots

[Benjamin R. <ben...@ou...>]

On Wed, Sep 26, 2012 at 5:58 AM, Pierre Haessig <pie...@cr...>wrote:

> Hello,
>
> In relation to the recent thread on pareto chart, I have a question with
> regards to the synchronization of ticks location when using twinx plots.
> This question may have been adressed in the past, but my Google search
> on this topic was unfruitful. Sorry if this question was already answered.
>
> Basically, when using twinx two plot two different data sets, the scale
> of the data, in the general case, is to be different (thus the need for
> twinx). However, adding a grid to such a twinx plot leads to a very
> irregular placement because the ticks positions are not "synchronized".
> (I pasted a quick example to illustrate the tick placement issue at the
> end of this message)
>
> Ideally, I would like that both axis share a common placement for the
> ticks. Is there a way to do that ?
>
> I guess this would require that the two ticks Locators share "some
> algorithm" so that they would "agree" on the placement instead of
> working separetely. Other option may be that one Locator could work as a
> slave of the other one. (I'm just trying to draw a rough picture)
>
> Best,
> Pierre
>
> quick example to illustrate the tick placement issue :
>
> import matplotlib.pyplot as plt
>
> ax1 = plt.subplot(111)
> ax1.plot([1,2,3], 'bo-')
> ax1.grid(True)
>
> ax2 = plt.twinx(ax1)
> ax2.plot([11,12], 'rs-')
> ax2.grid(True)
>
> ax1.set_xlim(-0.5,2.5)
>
> plt.show()
>
>
>
Probably could have the two axes listen for an "xlim_changed" event, check
to see if it belongs to its twin, and update itself accordingly (without
emitting).

Ben Root