matplotlib-users

Re: [Matplotlib-users] secondary y-axis

[Ryan K. <rya...@co...>]

If it helps clarify what I mean, attached is a plot I made in excel (I
really don't want to use excel).  The y-xis on the left goes from -60 to
80.  The one on the right goes from 0-1.

Ryan

Ryan Krauss wrote:
> Is it possible to overlay two plots with different y-axis limit?  I 
> think excel calls this plotting a data set with a secondary y-axis.  I 
> want to overlay a bode plot with its coherence and the y-axis limits for 
> the two will be very different.  I don't want to plot one above the 
> other with a subplot, but actually overlay them on the same plot.
> (and I want to do it on a semilogx).
> 
> Thanks,
> 
> Ryan
> 
> 
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Re: [Matplotlib-users] secondary y-axis

[Ryan K. <rya...@co...>]

It appears that this feature is available through the twinx() function 
according to:

http://matplotlib.sourceforge.net/faq.html#TWOSCALES
(the link on this page is broken, but I have the file in some examples I 
downloaded from somewhere else on the matplotlib page.)

I created the second plot using:
figure(1)
subplot(211)
ax2=pylab.twinx()
pylab.semilogx(freq,iobode.coh,'k')

It seems like once I called the twinx function, the x-axis settings that 
  where on the original axis are ignored and I can't seem to change the 
axis settings.  pylab.axes([0.1,30,0,1]) returned an error: 
RuntimeError: Transformation is not invertible

I tried calling the ax2.set_xlim((0.1,30)) function but it doesn't seem 
to do anything.

Ryan

Ryan Krauss wrote:
> If it helps clarify what I mean, attached is a plot I made in excel (I
> really don't want to use excel).  The y-xis on the left goes from -60 to
> 80.  The one on the right goes from 0-1.
> 
> Ryan
> 
> Ryan Krauss wrote:
> 
>> Is it possible to overlay two plots with different y-axis limit?  I 
>> think excel calls this plotting a data set with a secondary y-axis.  I 
>> want to overlay a bode plot with its coherence and the y-axis limits 
>> for the two will be very different.  I don't want to plot one above 
>> the other with a subplot, but actually overlay them on the same plot.
>> (and I want to do it on a semilogx).
>>
>> Thanks,
>>
>> Ryan
>>
>>
>> -------------------------------------------------------
>> This SF.Net email is sponsored by:
>> Power Architecture Resource Center: Free content, downloads, discussions,
>> and more. http://solutions.newsforge.com/ibmarch.tmpl
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
> 
> 
> ------------------------------------------------------------------------
> 

Re: [Matplotlib-users] secondary y-axis

[John H. <jdh...@ac...>]

>>>>> "Ryan" == Ryan Krauss <rya...@co...> writes:


    Ryan> It appears that this feature is available through the
    Ryan> twinx() function according to:

Right -- see also examples/two_scales.py

    Ryan> It seems like once I called the twinx function, the x-axis
    Ryan> settings that where on the original axis are ignored and I
    Ryan> can't seem to change the axis settings.
    Ryan> pylab.axes([0.1,30,0,1]) returned an error: RuntimeError:
    Ryan> Transformation is not invertible

Please post a free-standing, complete example which replicates the
bug.

Thanks,
JDH

Re: [Matplotlib-users] secondary y-axis

[Ryan K. <rya...@co...>]

This morning on my office computer I don't seem to have the same 
problem.  (I will see if I can recreate my problem on my laptop at home 
later.)

I do have one new problem though.  After adding the second plot, I need 
to refresh the legend of the first plot because the plot on twinx wrote 
over it.  Any calls to legend seem to be working with the lines that are 
drawn on twinx.  I could avoid this problem and make a slightly nicer 
looking plot if I could first draw on the twinx axis (with the y-axis 
ticks on the right) and then draw on the "normal" axis (with the y-axis 
ticks and label on the left).  Is this possible?

And can I make one legend that includes the plots from both axes?

Thanks for your help John.  I think I am getting close to a really nice 
graph with a lot of useful information on it.

Ryan



John Hunter wrote:
>>>>>>"Ryan" == Ryan Krauss <rya...@co...> writes:
> 
> 
> 
>     Ryan> It appears that this feature is available through the
>     Ryan> twinx() function according to:
> 
> Right -- see also examples/two_scales.py
> 
>     Ryan> It seems like once I called the twinx function, the x-axis
>     Ryan> settings that where on the original axis are ignored and I
>     Ryan> can't seem to change the axis settings.
>     Ryan> pylab.axes([0.1,30,0,1]) returned an error: RuntimeError:
>     Ryan> Transformation is not invertible
> 
> Please post a free-standing, complete example which replicates the
> bug.
> 
> Thanks,
> JDH
> 
> 
> -------------------------------------------------------
> This SF.Net email is sponsored by:
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> and more. http://solutions.newsforge.com/ibmarch.tmpl
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Re: [Matplotlib-users] secondary y-axis

[Ryan K. <rya...@co...>]

I am on my computer at home and can't recreate my problem.  I don't know 
what I did wrong last night.  I could still use help though on the 
legend refresh stuff in my other message.

Ryan Krauss wrote:
> This morning on my office computer I don't seem to have the same 
> problem.  (I will see if I can recreate my problem on my laptop at home 
> later.)
> 
> I do have one new problem though.  After adding the second plot, I need 
> to refresh the legend of the first plot because the plot on twinx wrote 
> over it.  Any calls to legend seem to be working with the lines that are 
> drawn on twinx.  I could avoid this problem and make a slightly nicer 
> looking plot if I could first draw on the twinx axis (with the y-axis 
> ticks on the right) and then draw on the "normal" axis (with the y-axis 
> ticks and label on the left).  Is this possible?
> 
> And can I make one legend that includes the plots from both axes?
> 
> Thanks for your help John.  I think I am getting close to a really nice 
> graph with a lot of useful information on it.
> 
> Ryan
> 
> 
> 
> John Hunter wrote:
> 
>>>>>>> "Ryan" == Ryan Krauss <rya...@co...> writes:
>>
>>
>>
>>
>>     Ryan> It appears that this feature is available through the
>>     Ryan> twinx() function according to:
>>
>> Right -- see also examples/two_scales.py
>>
>>     Ryan> It seems like once I called the twinx function, the x-axis
>>     Ryan> settings that where on the original axis are ignored and I
>>     Ryan> can't seem to change the axis settings.
>>     Ryan> pylab.axes([0.1,30,0,1]) returned an error: RuntimeError:
>>     Ryan> Transformation is not invertible
>>
>> Please post a free-standing, complete example which replicates the
>> bug.
>>
>> Thanks,
>> JDH
>>
>>
>> -------------------------------------------------------
>> This SF.Net email is sponsored by:
>> Power Architecture Resource Center: Free content, downloads, discussions,
>> and more. http://solutions.newsforge.com/ibmarch.tmpl
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
> 
> 
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Re: [Matplotlib-users] secondary y-axis

[John H. <jdh...@ac...>]

>>>>> "Ryan" == Ryan Krauss <rya...@co...> writes:

    Ryan> And can I make one legend that includes the plots from both
    Ryan> axes?

Save a list of lines and a list of labels and then call

    ax.legend(lines, labels)

lines and labels can be from different axes; eg,

    lines = []
    lines.extend( ax1.plot(something))
    lines.extend( ax2.plot(something_else))

See also the figure legend capability in
http://matplotlib.sf.net/matplotlib.figure.html

    Ryan> Thanks for your help John.  I think I am getting close to a
    Ryan> really nice graph with a lot of useful information on it.

Your welcome -- good luck.

JDH