matplotlib-users

[Matplotlib-users] Double y-axis with the same 0

[Daniele P. <dpa...@ya...>]

  Hi everybody,
I have a problem with a plot. I attach a figure to be easily understandable.

As you can see from the figure, I have in the same area a line and a bar 
plot. The problem is that y=0 for right y axis is different with respect 
to left y axis one. I want the two y=0 to be the same.

How can i do that?

Excuse me for my bad english, I'm italian :)

Thanks in advance.

Re: [Matplotlib-users] Double y-axis with the same 0

[Thøger E. J. T. <th...@fy...>]

One way is to specify the axes manually, e.g. setting:

(with matyplotlib.pyplot importad as plt:)

plt.axis([200, 500, -600, 600])

...or whatever seems fitting for you, and do that on both of the y axes.
That should align them nicely.

On Sat, 2010-07-17 at 20:37 +0200, Daniele Padula wrote:
> Hi everybody,
> I have a problem with a plot. I attach a figure to be easily understandable.
> 
> As you can see from the figure, I have in the same area a line and a bar 
> plot. The problem is that y=0 for right y axis is different with respect 
> to left y axis one. I want the two y=0 to be the same.
> 
> How can i do that?
> 
> Excuse me for my bad english, I'm italian :)
> 
> Thanks in advance.
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by Sprint
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Re: [Matplotlib-users] Double y-axis with the same 0

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

Somehow, this doesn't seem very satisfying.  It is almost accidental.  There
has to be a better way to do this.

Ben Root

2010/7/20 Thøger Emil Juul Thorsen <th...@fy...>

> One way is to specify the axes manually, e.g. setting:
>
> (with matyplotlib.pyplot importad as plt:)
>
> plt.axis([200, 500, -600, 600])
>
> ...or whatever seems fitting for you, and do that on both of the y axes.
> That should align them nicely.
>
> On Sat, 2010-07-17 at 20:37 +0200, Daniele Padula wrote:
> > Hi everybody,
> > I have a problem with a plot. I attach a figure to be easily
> understandable.
> >
> > As you can see from the figure, I have in the same area a line and a bar
> > plot. The problem is that y=0 for right y axis is different with respect
> > to left y axis one. I want the two y=0 to be the same.
> >
> > How can i do that?
> >
> > Excuse me for my bad english, I'm italian :)
> >
> > Thanks in advance.
> >
> ------------------------------------------------------------------------------
> > This SF.net email is sponsored by Sprint
> > What will you do first with EVO, the first 4G phone?
> > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
> > _______________________________________________ Matplotlib-users mailing
> list Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
>
>
> ------------------------------------------------------------------------------
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> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
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Re: [Matplotlib-users] Double y-axis with the same 0

[Thøger E. J. T. <th...@fy...>]

That really depends on what you want to do. For one single graph with
these specific values, it is quick and easy and hence very satisfying
*if that is what you need*. No need to go across the river for water.

But,  Daniele came up with a different and more sturdy solution (that I
have used in scripts of my own too), which is to specify the axes as
max-of-the-data-plus-a-bit reflected about a centered zero axis.
This is not data specific, more reusable, but also takes longer to
write. 

On Tue, 2010-07-20 at 15:28 -0500, Benjamin Root wrote:
> Somehow, this doesn't seem very satisfying.  It is almost accidental.
> There has to be a better way to do this.
> 
> Ben Root
> 
> 2010/7/20 Thøger Emil Juul Thorsen <th...@fy...>
>         One way is to specify the axes manually, e.g. setting:
>         
>         (with matyplotlib.pyplot importad as plt:)
>         
>         plt.axis([200, 500, -600, 600])
>         
>         ...or whatever seems fitting for you, and do that on both of
>         the y axes.
>         That should align them nicely.
>         
>         
>         On Sat, 2010-07-17 at 20:37 +0200, Daniele Padula wrote:
>         > Hi everybody,
>         > I have a problem with a plot. I attach a figure to be easily
>         understandable.
>         >
>         > As you can see from the figure, I have in the same area a
>         line and a bar
>         > plot. The problem is that y=0 for right y axis is different
>         with respect
>         > to left y axis one. I want the two y=0 to be the same.
>         >
>         > How can i do that?
>         >
>         > Excuse me for my bad english, I'm italian :)
>         >
>         > Thanks in advance.
>         
>         >
>         ------------------------------------------------------------------------------
>         > This SF.net email is sponsored by Sprint
>         > What will you do first with EVO, the first 4G phone?
>         > Visit sprint.com/first --
>         http://p.sf.net/sfu/sprint-com-first
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>         Matplotlib-users mailing list
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>         
>         
>         
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Re: [Matplotlib-users] Double y-axis with the same 0

[Daniele P. <dpa...@ya...>]

  I solved the problem and I'm going to explain the solution I used, it 
can be useful for someone.
y data for each series are contained into 2 different arrays, say y1 and 
y2.
The code is the sequent:

if max(y1) > max(y2):
     y_max = max(y1)
else:
     y_max = max(y2)

if min(y1) < min(y2):
     y_min= min(y1)
else:
     y_min = min(y2)

y_upper_limit = y_max+ y_max/10        # to leave some blank space on 
the top
y_lower_limit = y_min + y_min/10          # to leave some blank space on 
the bottom

Then, in your plot, you set ylim(y_lower_limit, y_upper_limit) and 
that's it.
This solution is good because it doesn't depend on the order of 
magnitude of the processed data, while specifying axes manually can give 
some problems for very different data sets.

I hope this message is correctly sent to the mailing list, the procedure 
for answering a message is not so immediate in my opinion.
Then, I subscribed the mailing list, so from the following messages (I 
have some other problems) I will use a different e-mail address.

Bye :)

Il 20/07/2010 22:28, Benjamin Root ha scritto:
> Somehow, this doesn't seem very satisfying.  It is almost accidental.  
> There has to be a better way to do this.
>
> Ben Root
>
> 2010/7/20 Thøger Emil Juul Thorsen <th...@fy... 
> <mailto:th...@fy...>>
>
>     One way is to specify the axes manually, e.g. setting:
>
>     (with matyplotlib.pyplot importad as plt:)
>
>     plt.axis([200, 500, -600, 600])
>
>     ...or whatever seems fitting for you, and do that on both of the y
>     axes.
>     That should align them nicely.
>
>     On Sat, 2010-07-17 at 20:37 +0200, Daniele Padula wrote:
>     > Hi everybody,
>     > I have a problem with a plot. I attach a figure to be easily
>     understandable.
>     >
>     > As you can see from the figure, I have in the same area a line
>     and a bar
>     > plot. The problem is that y=0 for right y axis is different with
>     respect
>     > to left y axis one. I want the two y=0 to be the same.
>     >
>     > How can i do that?
>     >
>     > Excuse me for my bad english, I'm italian :)
>     >
>     > Thanks in advance.
>     >
>     ------------------------------------------------------------------------------
>     > This SF.net email is sponsored by Sprint
>     > What will you do first with EVO, the first 4G phone?
>     > Visit sprint.com/first <http://sprint.com/first> --
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>     > _______________________________________________ Matplotlib-users
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>     https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
>
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