A quick way to do this is ``ax.invert_yaxis()`` (and invert_xaxis() for
the x-axis). That way you preserve auto-scaling and don't wind up with
manually set axis limits.
What you did should have worked, but ``ymin`` and ``ymax`` are probably
datetime objects. ``ylim`` isn't smart enough to convert them to the
datetime units that matplotlib uses internally.
Hope that helps!
-Joe
On Tue, Sep 16, 2014 at 4:00 AM, Gerd Wellenreuther <
gerd.wellenreut...@xfel.eu> wrote:
> 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 entry in stackoverflow which is most probably outdated, at least the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.
>
>
>
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