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

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

Tried this before, I think, here is the traceback (it is kind of 
different) - maybe it tells some of you where to look at IF this should 
really be a bug:

> 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.

Cheers, Gerd

On 16.09.2014 13:45, Joe Kington wrote:
> 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 
> <Ger...@xf... <mailto:Ger...@xf...>> 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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