Re: [Matplotlib-users] Multiplot with one colorbar

[Jody K. <jk...@uv...>]

Hi all,

Just to follow up, I wrote the following helper function to put a single colorbar to the right of a) an axes, b) a list of axes, c) to the right of a gridspec.  I was getting a little peeved with colorbar not working as I liked with subplots or gridspec, and this kind of does the trick for me for most of my use cases. 

I’m probably not the world’s best python programmer so feel free to make clearer.

Cheers,  Jody

def colorbarRight(pcm,ax,fig,shrink=0.7,width=0.025,gap=0.03,**kwargs):
    '''
    def colorbarRight(pcm,ax,fig,shrink=0.7,width=0.05,gap=0.02)
    
    Position colorbar to the right of axis 'ax' with colors from artist pcm.
    ax can be an array of axes such as that returned by "subplots".
    
    ax can also be a GridSpec, in which case the colorbar is centered to the
    right of the grid.  
    
    Defaults might no leave enough room for the colorbar on the right side, so 
    you should probably use subplots_adjust() or gridspec_update() to make more 
    space to the right:
    
    # with subplots:
    import matplotlib.pyplot as plt
    fig,ax=plt.subplots(2,2)
    fig.subplots_adjust(right=0.87)
    for axx in ax.flatten():
        pcm=axx.pcolormesh(rand(10,10))
    colorbarRight(pcm,ax,fig,extend='max')
    
    # with gridspec:
    import matplotlib.gridspec 
    import matplotlib.pyplot as plt
    fig=plt.figure()

    gs = gridspec.GridSpec(2,2)
    gs.update(right=0.87)
    for ii in range(2):
        for jj in range(2):
            ax=plt.subplot(gs[ii,jj])
            pcm=ax.pcolormesh(rand(10,10))
    colorbarRight(pcm,gs,fig,extend='max')
    '''
    import numpy as np

    if type(ax) is matplotlib.gridspec.GridSpec:
        # gridspecs are different than axes:
        pos = ax.get_grid_positions(fig)
        y0 = pos[0][-1]
        y1 = pos[1][0]
        x1 = pos[3][-1]
    else: 
        if ~(type(ax) is np.ndarray):
            # these are supposedly axes:
            ax=np.array(ax)
        # get max x1, min y0 and max y1
        y1 = 0.
        y0 = 1.
        x1=0.
        for axx in ax.flatten():
            pos=axx.get_position()
            x1=np.max([pos.x1,x1])
            y1=np.max([pos.y1,y1])
            y0=np.min([pos.y0,y0])
    height = y1-y0
    pos2 = [x1 + gap, y0 + (1.-shrink)*height/2.,  width, height*shrink]
    cax=axes(position=pos2)
    fig.colorbar(pcm,cax=cax,**kwargs)


> On 11 Mar 2015, at  19:43 PM, Dyah rahayu martiningrum <dya...@gm...> wrote:
> 
> Thank you so much Jody, Eric, Arnaldo, and Joy.
> I will try your suggestion.
> 
> 
> Dyah
> 
> On Sat, Mar 7, 2015 at 5:21 AM, Jody Klymak <jk...@uv... <mailto:jk...@uv...>> wrote:
> Hi,
> 
> I guess I don't understand the "[axx for axx in ax.flat]" command, but this steals from all the axes.
> 
> Cheers,   Jody
> 
> fig,ax = plt.subplots(2,2)
> for i in range(2):
>     for j in range(2):
>         im=ax[i,j].imshow(np.ones((20,20)))
>         im.set_clim([-1.,2.])
> cax,kw = mpl.colorbar.make_axes([axx for axx in ax.flat],shrink=0.5)
> plt.colorbar(im, cax=cax, **kw)
> 
> 
> > On Mar 6, 2015, at  9:39 AM, Eric Firing <ef...@ha... <mailto:ef...@ha...>> wrote:
> >
> > On 2015/03/05 11:36 PM, Dyah rahayu martiningrum wrote:
> >> Hello all,
> >>
> >> I make multi plot with colorbars. I need help, how do make only one
> >> colorbar for six panels? I also want to show only lowest x-axis. I copy
> >> my recent code and  figure here.
> >
> > An old example of something like this is here:
> >
> > http://matplotlib.org/examples/pylab_examples/multi_image.html <http://matplotlib.org/examples/pylab_examples/multi_image.html>
> >
> > Eric
> >
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> things parallel software development, from weekly thought leadership blogs to
> news, videos, case studies, tutorials and more. Take a look and join the
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> Dyah R Martiningrum
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> Graduate School of Informatics, Kyoto University
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Jody Klymak    
http://web.uvic.ca/~jklymak/