[Matplotlib-users] Inverting a datetime / plot_date y-axis

[Gerd W. <Ger...@xf...>]

Dear all,

I hope some of you could help me out. I am currently trying to generate 
some timetables using matplotlib.pyplot.plot_date, having the time-axis 
on the y-axis. Typically, one would like to read these plots from top to 
bottom, from older to newer items (future on the bottom). Unfortunately, 
the default enumeration of the y-axis is the other way around, and it 
resists my attempts to invert its direction e.g. by changing limits 
using matplotlib.pyplot.ylim (Traceback below). I found a quite old 
entry in stackoverflow which is most probably outdated, at least the 
proposed solution did not work for me... 
(http://stackoverflow.com/questions/5804969/displaying-an-inverted-vertical-date-axis).

Since the longish traceback seems to try to tell me I did not understand 
some kind of important - even trivial - point about those datetime-axis 
maybe some of you came about this problem before?

Thanks, Gerd

P.S.: Traceback after trying to use something like 
"matplotlib.pyplot.ylim(ymax,ymin)":
> Traceback (most recent call last):
>   File "C:\Users\gwellenr\Desktop\Test_Sabine\Plot_csv.py", line 187, 
> in <module>
>     matplotlib.pyplot.savefig(save_path+'test.png')
>   File "C:\Python27\lib\site-packages\matplotlib\pyplot.py", line 561, 
> in savefig
>     return fig.savefig(*args, **kwargs)
>   File "C:\Python27\lib\site-packages\matplotlib\figure.py", line 
> 1421, in savefig
>     self.canvas.print_figure(*args, **kwargs)
>   File "C:\Python27\lib\site-packages\matplotlib\backend_bases.py", 
> line 2220, in print_figure
>     **kwargs)
>   File 
> "C:\Python27\lib\site-packages\matplotlib\backends\backend_agg.py", 
> line 505, in print_png
>     FigureCanvasAgg.draw(self)
>   File 
> "C:\Python27\lib\site-packages\matplotlib\backends\backend_agg.py", 
> line 451, in draw
>     self.figure.draw(self.renderer)
>   File "C:\Python27\lib\site-packages\matplotlib\artist.py", line 55, 
> in draw_wrapper
>     draw(artist, renderer, *args, **kwargs)
>   File "C:\Python27\lib\site-packages\matplotlib\figure.py", line 
> 1034, in draw
>     func(*args)
>   File "C:\Python27\lib\site-packages\matplotlib\artist.py", line 55, 
> in draw_wrapper
>     draw(artist, renderer, *args, **kwargs)
>   File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 2086, 
> in draw
>     a.draw(renderer)
>   File "C:\Python27\lib\site-packages\matplotlib\artist.py", line 55, 
> in draw_wrapper
>     draw(artist, renderer, *args, **kwargs)
>   File "C:\Python27\lib\site-packages\matplotlib\axis.py", line 1091, 
> in draw
>     ticks_to_draw = self._update_ticks(renderer)
>   File "C:\Python27\lib\site-packages\matplotlib\axis.py", line 945, 
> in _update_ticks
>     tick_tups = [t for t in self.iter_ticks()]
>   File "C:\Python27\lib\site-packages\matplotlib\axis.py", line 889, 
> in iter_ticks
>     majorLocs = self.major.locator()
>   File "C:\Python27\lib\site-packages\matplotlib\dates.py", line 802, 
> in __call__
>     self.refresh()
>   File "C:\Python27\lib\site-packages\matplotlib\dates.py", line 820, 
> in refresh
>     self._locator = self.get_locator(dmin, dmax)
>   File "C:\Python27\lib\site-packages\matplotlib\dates.py", line 896, 
> in get_locator
>     raise ValueError('No sensible date limit could be found in the '
> ValueError: No sensible date limit could be found in the AutoDateLocator.